Wikipedia
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For Wikipedia's non-encyclopedic visitor introduction, please see Wikipedia:About.
Wikipedia
Screenshot of Wikipedia's multilingual portal
URL http://www.wikipedia.org/
Commercial? No
Type of site Internet encyclopedia project
Registration Optional
Available language(s): 236 active editions (253 in total)[1]
Owner Wikimedia Foundation
Created by Jimmy Wales, Larry Sanger[2]
Wikipedia (IPA: /ˌwikiˈpiːdi.ə/, /ˌwikiˈpeːdi.ə/ or /ˌwɪkiˈpiːdi.ə/ (Audio (U.S.) (help·info)) is a multilingual, web-based, free content encyclopedia project, operated by the Wikimedia Foundation, a non-profit organization.
As of July 20, 2007, Wikipedia has approximately 7.8 million articles in 253 languages, 1.9 million of which are in the English edition.[1] This makes it the largest, most extensive, and fastest growing encyclopedia ever compiled. It has been written collaboratively by volunteers around the world and the vast majority of its articles can be edited by anyone with access to the Internet. Steadily rising in popularity since its inception,[3] it currently ranks among the top ten most-visited websites worldwide.[4] Wikipedia's name is a portmanteau of the words wiki (a type of collaborative website) and encyclopedia. Its main servers are in Tampa, Florida, with additional servers located in Amsterdam and Seoul.
Due to Wikipedia's open nature, critics have questioned its reliability and accuracy.[5] The site has been criticized for its susceptibility to vandalism and the addition of false or unverified information,[6] uneven quality, systemic bias and inconsistencies,[7] and for favoring consensus over credentials in its editorial process.[8] Wikipedia's content policies[9] and sub-projects set up by contributors seek to address these concerns.[10] Two scholarly studies have concluded that vandalism is generally short-lived[11] and that Wikipedia is generally as accurate as other encyclopedias.[12]
Wikipedia along with other interactive websites such as YouTube and Facebook won the Time Person of the Year, awarded to the most influential of that year in 2006. The award was targeted at "you", praising the accelerating success of on-line collaboration and interaction by millions of users around the world, made possible through the World Wide Web. [13]
Contents [show]
1 Founding
2 Authorship and management
3 Software and hardware
4 Language editions
5 Content redistribution
6 Reliability and bias
7 Criticism and controversy
8 Awards
9 Cultural significance
10 Related projects
11 See also
12 References
13 External links
Founding
Main article: History of Wikipedia
Wikipedia's English edition was launched on January 15, 2001, as a complement to Nupedia, an expert-written and now defunct encyclopedia.
Jimmy Wales and Larry Sanger were identified as co-founders of Wikipedia in 2001. Wikipedia's official personnel page from September 2001 states that Wales and Sanger were the two co-founders, and that there was no editor-in-chief.[2][14][15][16][17] Wales, creator of the Wikimedia Foundation in 2003, today claims to be the sole founder of Wikipedia and has told The Boston Globe that "it's preposterous" to call Sanger the co-founder.[18] However, Sanger strongly contests that description. He was identified as a co-founder of Wikipedia at least as early as September 2001 and referred to himself that way as early as January 2002.[2][19][20]
Authorship and management
The original Wikipedia logoMaintenance tasks are performed by a group of volunteers; these include developers, who work on the MediaWiki software, and other trusted users with various permission levels including "steward", "bureaucrat" and "administrator."[21] Administrators are the largest group of specially privileged users, and have the ability to delete (remove) pages, lock articles from being changed, and deter users from editing.[22] Wikipedia is funded through the Wikimedia Foundation. Its 4th Quarter 2005 costs were $321,000 USD, with hardware making up almost 60% of the budget.[23] The Wikimedia Foundation currently relies primarily on private donations, and holds regular fundraisers;[24] the January 2007 fundraiser raised just over $1 million.[25]
Software and hardware
Wikipedia receives between 10,000 and 30,000 page requests per second, depending on time of day.[26] More than 100 servers have been set up to handle the traffic.The operation of Wikipedia depends on MediaWiki, a custom-made, free and open source wiki software platform written in PHP and built upon the MySQL database. The software incorporates modern programming features, such as a macro language, variables, a transclusion system for templates, and URL redirection. MediaWiki is licensed under the GNU General Public License and used by all Wikimedia projects, as well as many other wiki projects. Originally, Wikipedia ran on UseModWiki written in Perl by Clifford Adams (Phase I), which initially required CamelCase for article hyperlinks; the present double bracket style was incorporated later. Starting in January 2002 (Phase II), Wikipedia began running on a PHP wiki engine with a MySQL database; this software was custom-made for Wikipedia by Magnus Manske. The Phase II software was repeatedly modified to accommodate the exponentially increasing demand. In July 2002 (Phase III), Wikipedia shifted to the third-generation software, MediaWiki, originally written by Lee Daniel Crocker.
Overview of system architecture, May 2006. Source: layout diagrams Server layout diagrams on Meta-Wiki.Wikipedia runs on dedicated clusters of Linux servers in Florida and in four other locations.[27] Wikipedia employed a single server until 2004, when the server setup was expanded into a distributed multitier architecture. In January 2005, the project ran on 39 dedicated servers located in Florida. This configuration included a single master database server running MySQL, multiple slave database servers, 21 web servers running the Apache HTTP Server, and seven Squid cache servers. By September 2005, its server cluster had grown to around 100 servers in four locations around the world.[27]
Page requests are first passed to a front-end layer of Squid caching servers. Requests that cannot be served from the Squid cache are sent to load-balancing servers running the Linux Virtual Server software, which in turn pass the request to one of the Apache web servers for page rendering from the database. The web servers deliver pages as requested, performing page rendering for all the language editions of Wikipedia. To increase speed further, rendered pages for anonymous users are cached in a filesystem until invalidated, allowing page rendering to be skipped entirely for most common page accesses. Two larger clusters in the Netherlands and Korea now handle much of Wikipedia's traffic load.
Language editions
See also: List of Wikipedias
Wikipedia in Hebrew.[28]Wikipedia has been described as "an effort to create and distribute a free encyclopedia of the highest possible quality to every single person on the planet in their own language".[29] There are presently 253 language editions of Wikipedia; of these, the top 14 have over 100,000 articles and the top 139 have over 1,000 articles.[1]
Since Wikipedia is web-based and therefore worldwide, contributors of a same language edition may use different dialects or may come from different countries (this is the case for the English edition). These differences may lead to some conflicts about spelling[30] or points of view.[31] The English subdomain (en.wikipedia.org) receives approximately 51% of Wikipedia's cumulative traffic, with the remaining 49% split among the other languages (Spanish: 15%, Japanese 5%, German: 5%, French: 4%, Polish: 3%, Portuguese: 2%, Arabic: 2%).[3]
Though the various language editions are held to global policies such as "neutral point of view," they diverge on some points of policy and practice—most notably in their use of non-free images.[32][33]
Though each language edition functions more or less independently, some efforts are made to supervise them all. They are coordinated in part by Meta-Wiki, the Wikimedia Foundation's wiki devoted to maintaining all of its projects (Wikipedia and others). For instance, Meta-Wiki provides important statistics on all language editions of Wikipedia and maintain a list of articles every Wikipedia should have. The list concerns basic content by subject: biography, history, geography, society, culture, science, technology, foodstuffs, and mathematics. As for the rest, it is not rare for articles strongly related to a particular language not to have counterparts in another edition. For example, articles about small townships of the United States might only be available in English.
Multilingual editors of sufficient fluency are encouraged to translate articles manually; automated translation of articles is explicitly disallowed.[34] Translated articles represent only a small portion of articles in most editions.[35] Articles available in more than one language may offer "InterWiki" links, usually in their left margin, which link to the counterpart articles in other editions. Images and other non-verbal media are shared among the various language editions through the Wikimedia Commons repository. Beyond translations, some multilingual efforts are also realised thanks to the Multilingual coordination.
Content redistribution
Wikipedia's content has been mirrored and forked by many sites including database dumps.[citation needed] There is even a free downloadable DVD version[36] developed by Linterweb which contains "1964 + articles".[37][38]
Reliability and bias
English Wikipedia Main page on 4 July 2007Main article: Reliability of Wikipedia
Wikipedia appeals to the authority of peer-reviewed publications rather than the personal authority of experts. Wikipedia does not require that its contributors give their legal names or provide other information to establish their identity. Although some contributors are authorities in their field, Wikipedia requires that even their contributions be supported by published sources.
Wikipedia tries to address the problem of systemic bias, and to deal with zealous editors who seek to influence the presentation of an article in a biased way, by insisting on a neutral point of view. The English-language Wikipedia has introduced a scale against which the quality of articles is judged; other editions have also adopted this. Roughly 1200 articles have passed a rigorous set of criteria to reach the highest rank, "featured article" status; such articles are intended to provide thorough, well-written coverage of their topic, supported by many references to peer-reviewed publications.
In a study of Wikipedia as a community, economics PhD student Andrea Ciffolilli argued that the low transaction costs of participating in wiki software create a catalyst for collaborative development, and that a "creative construction" approach encourages participation.[39]
In February 2007, an article in The Harvard Crimson newspaper reported that some of the professors at Harvard University do include Wikipedia in their syllabus, but that there is a split in their perception of using Wikipedia.[40]
In June 2007, former president of the American Library Association Michael Gorman condemned Wikipedia, along with Google, for contributing to the creation of a generation of “intellectual sluggards”.[41] He also stated that academics who endorse the use of wikipedia are “the intellectual equivalent of a dietitian who recommends a steady diet of Big Macs with everything,” He also stated that “a generation of intellectual sluggards incapable of moving beyond the internet” was being produced at universities. He complains that the web-based sources are discouraging students from learning from the more rare texts which are either found only on paper or are on subscription-only web sites. In the same article Jenny Fry (a research fellow at the Oxford Internet Institute) commented on the academics who cite Wikipedia that:
“You cannot say children are intellectually lazy because they are using the internet when academics are using search engines in their research,” she said. “The difference is that they have more experience of being critical about what is retrieved and whether it is authoritative. Children need to be told how to use the internet in a critical and appropriate way.”[42]
Criticism and controversy
Main article: Criticism of Wikipedia
Wikipedia has been accused of exhibiting systemic bias and inconsistency;[5] critics argue that Wikipedia's open nature and a lack of proper sources for much of the information makes it unreliable.[43] Some commentators suggest that Wikipedia is usually reliable, but that it is not always clear how much.[8] The project's preference for consensus over credentials has been labeled "anti-elitism".[7] Editors of traditional reference works such as the Encyclopædia Britannica have questioned the project's utility and status as an encyclopedia.[44] Many university lecturers discourage students from citing any encyclopedia in academic work, preferring primary sources;[45] some specifically prohibit Wikipedia citations.[46] Co-founder Jimmy Wales stresses that encyclopedias of any type are not usually appropriate as primary sources, and should not be relied upon as authoritative.[47] Technology writer Bill Thompson commented that the debate was possibly "symptomatic of much learning about information which is happening in society today."[48]
Concerns have also been raised regarding the lack of accountability that results from users' anonymity,[49] and that it is vulnerable to vandalism and similar problems. In one particularly well-publicized incident, false information was introduced into the biography of John Seigenthaler, Sr. and remained undetected for four months.[50] Some critics claim that Wikipedia's open structure makes it an easy target for internet trolls, advertisers, and those with an agenda to push.[51][52] The addition of political spin to articles by organizations including the U.S. House of Representatives and special interest groups[6] has been noted,[53] and organizations such as Microsoft have offered financial incentives to work on certain articles.[54] Some claim that Wikipedia's political articles have been taken over by left-wing partisans.[55] These issues have been parodied, notably by Stephen Colbert in The Colbert Report.[56]
Wikipedia's community has been described as "cult-like,"[57] although not always with entirely negative connotations,[58] and criticised for failing to accommodate inexperienced users.[59]
Wikipedia's content policies[9] and sub-projects set up by contributors seek to address these concerns.[60] Several scholarly studies have concluded that vandalism is generally short-lived,[11] and that Wikipedia is roughly as accurate as other online encyclopedias.[12]
Awards
Wikipedia won two major awards in May 2004.[61] The first was a Golden Nica for Digital Communities of the annual Prix Ars Electronica contest; this came with a €10,000 (£6,588; $12,700) grant and an invitation to present at the PAE Cyberarts Festival in Austria later that year. The second was a Judges' Webby Award for the "community" category.[62] Wikipedia was also nominated for a "Best Practices" Webby. In September 2004, the Japanese Wikipedia was awarded a Web Creation Award from the Japan Advertisers Association. This award, normally given to individuals for great contributions to the Web in Japanese, was accepted by a long-standing contributor on behalf of the project.
In a 2006 Multiscope research study, the Dutch Wikipedia was rated the third best Dutch language site, after Google and Gmail, with a score of 8.1.[63] On 26 January 2007, Wikipedia was also awarded the fifth highest brand ranking by the readers of brandchannel.com, receiving 15% of the votes in answer to the question "Which brand had the most impact on our lives in 2006?"[64] Jimmy Wales was named one of the 100 most influential people in the world by TIME Magazine in 2006.[65] In 2006, the Russian Wikipedia won the "Science and education" category of the "Runet Prize" (Russian: Премия Рунета) award, supervised[66] by the Russian government agency FAPMC.
In November 2006, Turkish Wikipedia was nominated under the Science category for the Altın Örümcek Web Ödülleri (Golden Spider Web Awards), which are commonly known as the "Web Oscars" for Turkey. In January 2007, Turkish Wikipedia was given the award for "Best Content" in this competition. The award was given in a ceremony on 25 January 2007 at Istanbul Technical University.
Cultural significance
See also: Wikipedia in culture
Wikipedia's content has also been used in academic studies, books, conferences, and court cases.[67][68] The Canadian Parliament website refers to Wikipedia's article on same-sex marriage in the "related links" section of its "further reading" list for Civil Marriage Act.[69] The encyclopedia's assertions are increasingly used as a source by organizations such as the U.S. Federal Courts and the World Intellectual Property Office[70] — though mainly for supporting information rather than information decisive to a case.[71] Wikipedia has also been used as a source in journalism,[72] sometimes without attribution; several reporters have been dismissed for plagiarizing from Wikipedia.[73][74][75]
With increased usage and awareness, there have been an increasing number of references to Wikipedia in popular culture. Many parody Wikipedia's openness, with characters vandalizing or modifying the online encyclopedia project's articles. Notably, comedian Stephen Colbert has parodied or referenced Wikipedia on numerous episodes of his show The Colbert Report and coined the related term "wikiality".[56] Websites such as Uncyclopedia have also been set up parodying Wikipedia; its Main Page claims that it is the "content-free encyclopedia that anyone can edit,"[76] parodying the English Wikipedia's welcome message on its Main Page.
Related projects
A number of interactive multimedia encyclopedias incorporating entries written by the public existed long before Wikipedia was founded. The first of these was the 1986 BBC Domesday Project, which included text (entered on BBC Micro computers) and photographs from over 1 million contributors in the UK, and covering the geography, art and culture of the UK. This was the first interactive multimedia encyclopedia (and was also the first major multimedia document connected through internal links), with the majority of articles being accessible through an interactive map of the UK. The user-interface and part of the content of the Domesday Project have now been emulated on a website[77]. One of the most successful early online encyclopedias incorporating entries by the public was h2g2, which was also created by the BBC. The h2g2 encyclopedia was relatively light-hearted, focusing on articles which were both witty and informative. Both of these projects had similarities with Wikipedia, but neither gave full editorial freedom to public users.
Wikipedia has also spawned several sister projects. The first, "In Memoriam: September 11 Wiki",[78] created in October 2002,[79] detailed the September 11, 2001 attacks; this project was closed in October 2006.[80] Wiktionary, a dictionary project, was launched in December 2002;[81] Wikiquote, a collection of quotations, a week after Wikimedia launched, and Wikibooks, a collection of collaboratively written free books, the next month. Wikimedia has since started a number of other projects.[82]
A similar non-wiki project, the GNUpedia project, co-existed with Nupedia early in its history; however, it has been retired and its creator, free-software figure Richard Stallman, has lent his support to Wikipedia.[83]
Other websites centered on collaborative knowledge base development have drawn inspiration from or inspired Wikipedia. Some, such as Susning.nu, Enciclopedia Libre, and WikiZnanie likewise employ no formal review process, whereas others use more traditional peer review, such as the expert-written Stanford Encyclopedia of Philosophy, h2g2 and Everything2.
Conservapedia is a wiki encyclopedia project with goals similar to Wikipedia, but attempts to write articles from a socially and economically conservative perspective. It was started in late 2006 by Andrew Schlafly, a son of Phyllis Schlafly, who felt Wikipedia had a liberal bias in its articles. Conservapedia is not affiliated with Wikipedia or Wikipedia's parent organization, the Wikimedia Foundation, although both use the free MediaWiki software to power their site.
Jimmy Wales, the de facto leader of Wikipedia,[84] said in an interview in regard to the online encyclopedia Citizendium which is overviewed by experts in their respective fields:[85] "We welcome a diversity of efforts. If Larry's project is able to produce good work, we will benefit from it by copying it back into Wikipedia."[86]
Tuesday, July 24, 2007
Monday, July 23, 2007
About Google
Google Inc. (NASDAQ: GOOG and LSE: GGEA) is an American public corporation, specializing in Internet search and online advertising. The company is based in Mountain View, California, and has 13,748 full-time employees (as of June 30, 2007).[2] Google's mission statement is, "to organize the world's information and make it universally accessible and useful."[3] Google's corporate philosophy includes statements such as "Don't be evil", and "Work should be challenging and the challenge should be fun", illustrating a somewhat relaxed corporate culture.
Google was co-founded by Larry Page and Sergey Brin while they were students at Stanford University and the company was first incorporated as a privately held company on September 7, 1998. Google's initial public offering took place on August 19, 2004, raising $1.67 billion, making it worth $23 billion. Through a series of new product developments, acquisitions and partnerships, the company has expanded its initial search and advertising business into other areas, including web-based email, online mapping, office productivity, and video sharing, among others.
Like most large corporations, Google's businesses have drawn some controversy, such as copyright disputes in its book search project, or censorship by Google of search results as it works with countries such as China (and to a lesser extent France, Germany), which have laws requiring the company hide information from Google users in their country. Additionally, in the post September 11 era, several governments and militaries have raised concerns about the national security risks posed by vivid geographic details provided by Google Earth's satellite imaging.
Contents [show]
1 History
1.1 Financing and initial public offering
1.2 Growth
1.3 Acquisitions
1.4 Partnerships
2 Products
2.1 Advertising
2.2 Applications
2.3 Enterprise products
3 Platform
4 Corporate affairs and culture
4.1 Googleplex
4.2 "Twenty percent" time
4.3 Easter eggs and April Fool's Day jokes
4.4 IPO and culture
5 Criticism
6 See also
7 References
8 Further reading
9 External links
[edit] History
Google in 1998Main article: History of Google
Google began as a research project in January 1996 by Larry Page and Sergey Brin, two Ph.D. students at Stanford University, California.[4] They hypothesized that a search engine that analyzed the relationships between websites would produce better results than existing techniques, which ranked results according to the number of times the search term appeared on a page.[5] Their search engine was originally nicknamed, "BackRub" because the system checked backlinks to estimate a site's importance.[6] A small search engine called Rankdex was already exploring a similar strategy.[7] Convinced that the pages with the most links to them from other highly relevant web pages must be the most relevant pages associated with the search, Page and Brin tested their thesis as part of their studies, and laid the foundation for their search engine. Originally the search engine used the Stanford University website with the domain google.stanford.edu. The domain google.com was registered on September 14, 1997, and the company was incorporated as Google Inc. on September 7, 1998 at a friend's garage in Menlo Park, California. The total initial investment raised for the new company eventually amounted to almost $1.1 million, including a $100,000 check by Andy Bechtolsheim, one of the founders of Sun Microsystems.[8]
In March 1998, the company moved into offices at 165 University Avenue in Palo Alto, home to several other noted Silicon Valley technology startups.[9] After quickly outgrowing two other sites, the company leased a complex of buildings in Mountain View at 1600 Amphitheatre Parkway from Silicon Graphics (SGI) in 2003.[10] The company has remained at this location ever since, and the complex has since become known as the Googleplex (a play on the word googolplex, a 1 followed by a googol zeros). In 2006, Google bought the property from SGI for $319 million.[11]
The Google search engine attracted a loyal following among the growing number of Internet users, who liked its simple design.[12] In 2000, Google began selling advertisements associated with search keywords.[4] The ads were text-based to maintain an uncluttered page design and to maximize page loading speed.[4] Keywords were sold based on a combination of price bid and clickthroughs, with bidding starting at $.05 per click.[4] This model of selling keyword advertising was pioneered by Goto.com (later renamed Overture Services, before being acquired by Yahoo! and rebranded as Yahoo! Search Marketing).[13][14][15] While many of its dot-com rivals failed in the new Internet marketplace, Google quietly rose in stature while generating revenue.[4]
The name "Google" originated from a misspelling of "googol,"[16][17] which refers to 10100 (the number represented by a 1 followed by one-hundred zeros). Having found its way increasingly into everyday language, the verb, "google", was added to the Merriam Webster Collegiate Dictionary and the Oxford English Dictionary in 2006, meaning, "to use the Google search engine to obtain information on the Internet."[18][19]
A patent describing part of Google's ranking mechanism (PageRank) was granted on September 4, 2001.[20] The patent was officially assigned to Stanford University and lists Lawrence Page as the inventor.
[edit] Financing and initial public offering
The first funding for Google as a company was secured in the form of a USD100,000 contribution from Andy Bechtolsheim, co-founder of Sun Microsystems, given to a corporation which did not yet exist.[21] Around six months later, a much larger round of funding was announced, with the major investors being rival venture capital firms Kleiner Perkins Caufield & Byers and Sequoia Capital.[21]
Google's initial public offering took place on August 19, 2004. 19,605,052 shares were offered at a price of $85 per share.[22] Of that, 14,142,135 (another mathematical reference as √2 ≈ 1.4142135) were floated by Google and 5,462,917 by selling stockholders. The sale raised $1.67 billion, and gave Google a market capitalization of more than $23 billion.[23] The vast majority of Google's 271 million shares remained under Google's control. Many of Google's employees became instant paper millionaires. Yahoo!, a competitor of Google, also benefited from the IPO because it owns 2.7 million shares of Google.[24]
Google's post-IPO stock performance has been very good as well, with shares surging to $500 by 2007, due to strong sales and earnings in the advertising market, as well as the release of new features like the desktop search function and personalized home page.[25] The surge in stock price is fueled primarily by individual investors, as opposed to large institutional investors and mutual funds.[25]
The company is listed on the NASDAQ stock exchange under the ticker symbol GOOG.
[edit] Growth
While the company's primary market is in the web content arena, Google has begun to experiment with other markets, such as radio and print publications. On January 17, 2006, Google announced that it had purchased the radio advertising company dMarc, which provides an automated system that allows companies to advertise on the radio.[26] This will allow Google to combine two niche advertising media—the Internet and radio—with Google's ability to laser-focus on the tastes of consumers. Google has also begun an experiment in selling advertisements from its advertisers in offline newspapers and magazines, with select advertisements in the Chicago Sun-Times.[27] They have been filling unsold space in the newspaper that would have normally been used for in-house advertisements.
Google was added to the S&P 500 index on March 30, 2006. Google replaced Burlington Resources, a major oil producer based in Houston which was acquired by ConocoPhillips.
[edit] Acquisitions
See also: List of Google acquisitions
Since 2001, Google has acquired several small start-up companies, often consisting of innovative teams and products. One of the earlier companies that Google bought was Pyra Labs. They were the creators of Blogger, a weblog publishing platform, first launched in 1999. This acquisition led to many premium features becoming free. Pyra Labs was originally formed by Evan Williams, yet he left Google in 2004. In early 2006, Google acquired Upstartle, a company responsible for the online word processor, Writely. The technology in this product was used by Google to eventually create Google Docs & Spreadsheets.
In February 2006, software company Adaptive Path sold Measure Map, a weblog statistics application, to Google. Registration to the service has since been temporarily disabled.
In late 2006, Google bought online video site YouTube for $1.65 billion in stock.[28] Shortly after, on October 31, 2006, Google announced that it had also acquired JotSpot, a developer of wiki technology for collaborative Web sites.[29]
On April 13, 2007, Google reached an agreement to acquire DoubleClick. Google agreed to buy the company for $3.1 billion.[30]
On July 9, 2007, Google announced that it had signed a definitive agreement to acquire enterprise messaging security and compliance company Postini.[31]
[edit] Partnerships
In 2005, Google entered into partnerships with other companies and government agencies to improve production and services. Google announced a partnership with NASA Ames Research Center to build up 1 million square feet of offices and work on research projects involving large-scale data management, nanotechnology, distributed computing, and the entrepreneurial space industry.[32] Google also entered into a partnership with Sun Microsystems in October to help share and distribute each other's technologies.[33] The company entered into a partnership with Time Warner's America Online,[34] to enhance each other's video search services.
In 2006, Google and News Corp.'s Fox Interactive Media entered into a $900 million agreement to provide search and advertising on the popular social networking site, MySpace.[35]
[edit] Products
Main article: List of Google products
Google has created services and tools for the general public and business environment alike; including Web applications, advertising networks and solutions for businesses.
[edit] Advertising
Most of Google's revenue is derived from advertising programs. For the 2006 fiscal year, the company reported $10.492 billion in total advertising revenues and only $112 million in licensing and other revenues.[36] Google AdWords allows Web advertisers to display advertisements in Google's search results and the Google Content Network, through either a cost-per-click or cost-per-view scheme. Google AdSense website owners can also display adverts on their own site, and earn money every time ads are clicked.
[edit] Applications
Google is well-known for its web search service, which is a major factor of the company's success. As of December 2006, Google is the most used search engine on the web with a 50.8% market share, ahead of Yahoo! (23.6%) and Windows Live Search (8.4%).[37] Google indexes billions of Web pages, so that users can search for the information they desire, through the use of keywords and operators. Google has also employed the Web Search technology into other search services, including Image Search, Google News, the price comparison site Google Product Search, the interactive Usenet archive Google Groups, Google Maps and more.
In 2004, Google launched its own free web-based email service, known as Gmail.[38] Gmail features spam filtering technology and the capability to use Google technology to search email. The service generates revenue by displaying advertisements from the AdWords service that are tailored to the content of the email messages displayed on screen.
In early 2006, the company launched Google Video, which not only allows users to search and view freely available videos, but also offers users and media publishers the ability to publish their content, including television shows on CBS, NBA basketball games, and music videos.[39]
Google has also developed several desktop applications, including Google Earth, an interactive mapping program powered by satellite imagery that covers the vast majority of the earth. Google Earth is generally considered to be remarkably accurate and extremely detailed. For example, some major cities (Las Vegas, NV, USA for example) have such detailed images that one can zoom in close enough to read the license plates on cars on a street. Consequently, there have been some concerns about national security implications. Specifically, some countries and militaries contend the software can be used to pinpoint with near-precision accuracy the physical location of critical infrastructure, commercial and residential buildings, bases, government agencies, and so on. However, the satellite images are not necessarily frequently updated, and all of them are available at no charge through other products and even government sources (NASA and the National Geospatial-Intelligence Agency, for example.) Some counter this argument by stating that Google Earth makes it easier to access and research the images.
Many other products are available through Google Labs, which is a collection of incomplete applications that are still being tested for use by the general public.
Google has promoted their products in various ways. In London, Google Space was set-up in Heathrow Airport, showcasing several products, including Gmail, Google Earth and Picasa.[40][41] Also, a similar page was launched for American college students, under the name College Life, Powered by Google.[42]
In 2007, some reports surfaced that Google was planning the release of its own mobile phone, possibly a competitor to Apple's iPhone.[43][44][45] The project may be a collaboration between Google and Orange, HTC, Samsung, or another manufacturer. However, very little is known about the project and most of the information available is speculation.
[edit] Enterprise products
In 2007, Google launched Google Apps Premium Edition, a software suite for businesses that provides e-mail, instant messaging, calendar, word processing, as well as a spreadsheet program.[46] This product is targeted primarily at the business user, and intended to compete directly versus Microsoft's Office suite, with a price of approximately USD50 per user per year compared to USD500 per user for Microsoft Office.[46] A large implementation of Google Apps with 38,000 users is at Lakehead University in Thunder Bay, Ontario, Canada.[47]
[edit] Platform
Main article: Google platform
Google's services are run on several server farms, each consisting of thousands of low-cost commodity computers running stripped-down versions of Linux. While the company does not provide detailed information about its hardware, a 2006 estimate consisted of over 450,000 servers, racked up in clusters located in data centers around the world.[48]
[edit] Corporate affairs and culture
A license plate seen in the Googleplex parking lot.Google is particularly known for its relaxed corporate culture, reminiscent of the Dot-com boom. In January 2007, it was cited by Fortune Magazine as the #1 (of 100) best company to work for.[49] Google's corporate philosophy is based on many casual principles including, "You can make money without doing evil", "You can be serious without a suit," and "Work should be challenging and the challenge should be fun." A complete list of corporate fundamentals is available on Google's website.[50] Google's relaxed corporate culture can also be seen externally through their holiday variations of the Google logo.
Typical salaries at Google are considered to be quite low by industry standards.[citation needed] For example, some system administrators earn no more than $35,000 per year – considered to be quite low for the Bay Area job market.[51] However, Google's stock performance following its IPO has enabled many early employees to be competitively compensated by participation in the corporation's remarkable equity growth.[52] Google implemented other employee incentives in 2005, such as the Google Founders' Award, in addition to offering higher salaries to new employees. Google's workplace amenities, culture, global popularity, and strong brand recognition have also attracted potential applicants.
After the company's IPO in August 2004, it was reported that founders Sergey Brin and Larry Page, and CEO Eric Schmidt, requested that their base salary be cut to $1.00.[53] Subsequent offers by the company to increase their salaries have been turned down, primarily because, "their primary compensation continues to come from returns on their ownership stakes in Google. As significant stockholders, their personal wealth is tied directly to sustained stock price appreciation and performance, which provides direct alignment with stockholder interests."[53] Prior to 2004, Schmidt was making $250,000 per year, and Page and Brin each earned a salary of $150,000.[53]
They have all declined recent offers of bonuses and increases in compensation by Google's board of directors. In a 2006 report of the United States' richest people, Forbes reported that Sergey Brin was #12 with a net worth of $14.1 billion, and Larry Page was #13 with a net worth of $14.0 billion.[54]
[edit] Googleplex
The GoogleplexMain article: Googleplex
As a play on Google's name, its headquarters, in Mountain View, California, is referred to as "the Googleplex" — a googolplex being 1 followed by a googol of zeros, and the HQ being a complex of buildings (cf. multiplex, cineplex, etc). The lobby is decorated with a piano, lava lamps, old server clusters, and a projection of search queries on the wall. The hallways are full of exercise balls and bicycles. Each employee has access to the corporate recreation center. Recreational amenities are scattered throughout the campus and include a workout room with weights and rowing machines, locker rooms, washers and dryers, a massage room, assorted video games, Foosball, a baby grand piano, a pool table, and ping pong. In addition to the rec room, there are snack rooms stocked with various cereals, gummy bears, toffee, licorice, cashews, yogurt, carrots, fresh fruit, and dozens of different drinks including fresh juice, soda, and make your own cappuccino.
Sign at the GoogleplexIn 2006, Google moved into 311,000 square feet of office space in New York City, at 111 Eighth Ave. in Manhattan.[55] The office was specially designed and built for Google and houses its largest advertising sales team, which has been instrumental in securing large partnerships, most recently deals with MySpace and AOL.[55] In 2003, they added an engineering staff in New York City, which has been responsible for more than 100 engineering projects, including Google Maps, Google Spreadsheets, and others.[55] It is estimated that the building costs Google $10 million per year to rent and is similar in design and functionality to its Mountain View headquarters, including Foosball, air hockey, and ping-pong tables, as well as a video game area.[55]
Google is also making steps to ensure that their operations are environmentally sound. In October 2006, the company announced plans to install thousands of solar panels to provide up to 1.6 megawatts of electricity, enough to satisfy approximately 30% of the campus' energy needs.[56] The system will be the largest solar power system constructed on a U.S. corporate campus and one of the largest on any corporate site in the world.[56] In June 2007, Google announced that they plan to become carbon neutral by 2008, which includes investing in energy efficiency, renewable energy sources, and purchasing carbon offsets, such as investing in projects like capturing and burning methane from animal waste at Mexican and Brazilian farms.[57]
[edit] "Twenty percent" time
All Google engineers are encouraged to spend 20% of their work time (one day per week) on projects that interest them. Some of Google's newer services, such as Gmail, Google News, Orkut, and AdSense originated from these independent endeavors.[58] In a talk at Stanford University, Marissa Mayer, Google's vice president of search products and user experience, stated that her analysis showed that half of the new product launches originated from the 20% time.[59]
[edit] Easter eggs and April Fool's Day jokes
Main article: Google's hoaxes
Google has a tradition of creating April Fool's Day jokes — such as Google MentalPlex, which allegedly featured the use of mental power to search the web.[60] In 2002, they claimed that pigeons were the secret behind their growing search engine.[61] In 2004, they featured Google Lunar (which claimed to feature jobs on the moon),[62] and in 2005, a fictitious brain-boosting drink, termed Google Gulp was announced.[63] In 2006, they came up with Google Romance, a hypothetical online dating service.[64] In 2007, Google announced two joke products. The first was a free wireless Internet service called TiSP (Toilet Internet Service Provider) [65] in which one obtained a connection by flushing one end of a fiber-optic cable down their toilet and waiting only an hour for a "Plumbing Hardware Dispatcher (PHD)" to connect it to the Internet.[65] Additionally, Google's Gmail page displayed an announcement for Gmail Paper, which allows users of their free email service to have email messages printed and shipped to a snail mail address.[66]
Some thought the announcement of Gmail in 2004 around April Fool's Day (as well as the doubling of Gmail's storage space to two gigabytes in 2005) was a joke, although both of these turned out to be genuine announcements. In 2005, a comedic graph depicting Google's goal of "infinity plus one" GB of storage was featured on the Gmail homepage.
Google's services contain a number of Easter eggs; for instance, the Language Tools page offers the search interface in the Swedish Chef's "Bork bork bork," Pig Latin, ”Hacker” (Actually leetspeak), Elmer Fudd, and Klingon.[67] When asked how to get from a location in the U.S. to a location in Europe, Google Maps will provide directions that include an instruction to "Swim across the Atlantic Ocean." [68] In addition, the search engine calculator provides The Answer to Life, the Universe, and Everything from Douglas Adams' The Hitchhiker's Guide to the Galaxy.[69] As Google's search box can be used as a unit converter (as well as a calculator), some non-standard units are built in, such as the Smoot. Google also routinely modifies its logo in accordance with various holidays or special events throughout the year, such as Christmas, Mother's Day, or various birthdays of notable individuals.[70]
[edit] IPO and culture
Many people speculated that Google's IPO would inevitably lead to changes in the company's culture,[71] because of shareholder pressure for employee benefit reductions and short-term advances, or because a large number of the company's employees would suddenly become millionaires on paper. In a report given to potential investors, co-founders Sergey Brin and Larry Page promised that the IPO would not change the company's culture.[72] Later Mr. Page said, "We think a lot about how to maintain our culture and the fun elements. We spent a lot of time getting our offices right. We think it's important to have a high density of people. People are packed together everywhere. We all share offices. We like this set of buildings because it's more like a densely packed university campus than a typical suburban office park."[73]
However, many analysts are finding that as Google grows the company is becoming more "corporate". In 2005, articles in The New York Times and other sources began suggesting that Google had lost its anti-corporate, no evil philosophy.[74][75] In an effort to maintain the company's unique culture, Google has designated a Chief Culture Officer in 2006, who also serves as the Director of Human Resources. The purpose of the Chief Culture Officer is to develop and maintain the culture and work on ways to keep true to the core values that the company was founded on in the beginning — a flat organization, a lack of hierarchy, a collaborative environment.[76]
[edit] Criticism
Main article: Criticism of Google
As it has grown, Google has found itself the focus of several controversies related to its business practices and services. For example, Google Book Search's effort to digitize millions of books and make the full text searchable has led to copyright disputes with the Authors Guild. Google's cooperation with the governments of China, and to a lesser extent France and Germany (regarding Holocaust denial) to filter search results in accordance to regional laws and regulations has led to claims of censorship. Google's persistent cookie and other information collection practices have led to concerns over user privacy. A number of governments have raised concerns about the security risks posed by geographic details provided by Google Earth's satellite imaging.[77] Google has also been criticized by advertisers regarding its inability to combat click fraud, when a person or automated script is used to generate a charge on an advertisement without really having an interest in the product. Industry reports in 2006 claim that approximately 14 to 20 percent of clicks were in fact fraudulent or invalid.[78]
Google was co-founded by Larry Page and Sergey Brin while they were students at Stanford University and the company was first incorporated as a privately held company on September 7, 1998. Google's initial public offering took place on August 19, 2004, raising $1.67 billion, making it worth $23 billion. Through a series of new product developments, acquisitions and partnerships, the company has expanded its initial search and advertising business into other areas, including web-based email, online mapping, office productivity, and video sharing, among others.
Like most large corporations, Google's businesses have drawn some controversy, such as copyright disputes in its book search project, or censorship by Google of search results as it works with countries such as China (and to a lesser extent France, Germany), which have laws requiring the company hide information from Google users in their country. Additionally, in the post September 11 era, several governments and militaries have raised concerns about the national security risks posed by vivid geographic details provided by Google Earth's satellite imaging.
Contents [show]
1 History
1.1 Financing and initial public offering
1.2 Growth
1.3 Acquisitions
1.4 Partnerships
2 Products
2.1 Advertising
2.2 Applications
2.3 Enterprise products
3 Platform
4 Corporate affairs and culture
4.1 Googleplex
4.2 "Twenty percent" time
4.3 Easter eggs and April Fool's Day jokes
4.4 IPO and culture
5 Criticism
6 See also
7 References
8 Further reading
9 External links
[edit] History
Google in 1998Main article: History of Google
Google began as a research project in January 1996 by Larry Page and Sergey Brin, two Ph.D. students at Stanford University, California.[4] They hypothesized that a search engine that analyzed the relationships between websites would produce better results than existing techniques, which ranked results according to the number of times the search term appeared on a page.[5] Their search engine was originally nicknamed, "BackRub" because the system checked backlinks to estimate a site's importance.[6] A small search engine called Rankdex was already exploring a similar strategy.[7] Convinced that the pages with the most links to them from other highly relevant web pages must be the most relevant pages associated with the search, Page and Brin tested their thesis as part of their studies, and laid the foundation for their search engine. Originally the search engine used the Stanford University website with the domain google.stanford.edu. The domain google.com was registered on September 14, 1997, and the company was incorporated as Google Inc. on September 7, 1998 at a friend's garage in Menlo Park, California. The total initial investment raised for the new company eventually amounted to almost $1.1 million, including a $100,000 check by Andy Bechtolsheim, one of the founders of Sun Microsystems.[8]
In March 1998, the company moved into offices at 165 University Avenue in Palo Alto, home to several other noted Silicon Valley technology startups.[9] After quickly outgrowing two other sites, the company leased a complex of buildings in Mountain View at 1600 Amphitheatre Parkway from Silicon Graphics (SGI) in 2003.[10] The company has remained at this location ever since, and the complex has since become known as the Googleplex (a play on the word googolplex, a 1 followed by a googol zeros). In 2006, Google bought the property from SGI for $319 million.[11]
The Google search engine attracted a loyal following among the growing number of Internet users, who liked its simple design.[12] In 2000, Google began selling advertisements associated with search keywords.[4] The ads were text-based to maintain an uncluttered page design and to maximize page loading speed.[4] Keywords were sold based on a combination of price bid and clickthroughs, with bidding starting at $.05 per click.[4] This model of selling keyword advertising was pioneered by Goto.com (later renamed Overture Services, before being acquired by Yahoo! and rebranded as Yahoo! Search Marketing).[13][14][15] While many of its dot-com rivals failed in the new Internet marketplace, Google quietly rose in stature while generating revenue.[4]
The name "Google" originated from a misspelling of "googol,"[16][17] which refers to 10100 (the number represented by a 1 followed by one-hundred zeros). Having found its way increasingly into everyday language, the verb, "google", was added to the Merriam Webster Collegiate Dictionary and the Oxford English Dictionary in 2006, meaning, "to use the Google search engine to obtain information on the Internet."[18][19]
A patent describing part of Google's ranking mechanism (PageRank) was granted on September 4, 2001.[20] The patent was officially assigned to Stanford University and lists Lawrence Page as the inventor.
[edit] Financing and initial public offering
The first funding for Google as a company was secured in the form of a USD100,000 contribution from Andy Bechtolsheim, co-founder of Sun Microsystems, given to a corporation which did not yet exist.[21] Around six months later, a much larger round of funding was announced, with the major investors being rival venture capital firms Kleiner Perkins Caufield & Byers and Sequoia Capital.[21]
Google's initial public offering took place on August 19, 2004. 19,605,052 shares were offered at a price of $85 per share.[22] Of that, 14,142,135 (another mathematical reference as √2 ≈ 1.4142135) were floated by Google and 5,462,917 by selling stockholders. The sale raised $1.67 billion, and gave Google a market capitalization of more than $23 billion.[23] The vast majority of Google's 271 million shares remained under Google's control. Many of Google's employees became instant paper millionaires. Yahoo!, a competitor of Google, also benefited from the IPO because it owns 2.7 million shares of Google.[24]
Google's post-IPO stock performance has been very good as well, with shares surging to $500 by 2007, due to strong sales and earnings in the advertising market, as well as the release of new features like the desktop search function and personalized home page.[25] The surge in stock price is fueled primarily by individual investors, as opposed to large institutional investors and mutual funds.[25]
The company is listed on the NASDAQ stock exchange under the ticker symbol GOOG.
[edit] Growth
While the company's primary market is in the web content arena, Google has begun to experiment with other markets, such as radio and print publications. On January 17, 2006, Google announced that it had purchased the radio advertising company dMarc, which provides an automated system that allows companies to advertise on the radio.[26] This will allow Google to combine two niche advertising media—the Internet and radio—with Google's ability to laser-focus on the tastes of consumers. Google has also begun an experiment in selling advertisements from its advertisers in offline newspapers and magazines, with select advertisements in the Chicago Sun-Times.[27] They have been filling unsold space in the newspaper that would have normally been used for in-house advertisements.
Google was added to the S&P 500 index on March 30, 2006. Google replaced Burlington Resources, a major oil producer based in Houston which was acquired by ConocoPhillips.
[edit] Acquisitions
See also: List of Google acquisitions
Since 2001, Google has acquired several small start-up companies, often consisting of innovative teams and products. One of the earlier companies that Google bought was Pyra Labs. They were the creators of Blogger, a weblog publishing platform, first launched in 1999. This acquisition led to many premium features becoming free. Pyra Labs was originally formed by Evan Williams, yet he left Google in 2004. In early 2006, Google acquired Upstartle, a company responsible for the online word processor, Writely. The technology in this product was used by Google to eventually create Google Docs & Spreadsheets.
In February 2006, software company Adaptive Path sold Measure Map, a weblog statistics application, to Google. Registration to the service has since been temporarily disabled.
In late 2006, Google bought online video site YouTube for $1.65 billion in stock.[28] Shortly after, on October 31, 2006, Google announced that it had also acquired JotSpot, a developer of wiki technology for collaborative Web sites.[29]
On April 13, 2007, Google reached an agreement to acquire DoubleClick. Google agreed to buy the company for $3.1 billion.[30]
On July 9, 2007, Google announced that it had signed a definitive agreement to acquire enterprise messaging security and compliance company Postini.[31]
[edit] Partnerships
In 2005, Google entered into partnerships with other companies and government agencies to improve production and services. Google announced a partnership with NASA Ames Research Center to build up 1 million square feet of offices and work on research projects involving large-scale data management, nanotechnology, distributed computing, and the entrepreneurial space industry.[32] Google also entered into a partnership with Sun Microsystems in October to help share and distribute each other's technologies.[33] The company entered into a partnership with Time Warner's America Online,[34] to enhance each other's video search services.
In 2006, Google and News Corp.'s Fox Interactive Media entered into a $900 million agreement to provide search and advertising on the popular social networking site, MySpace.[35]
[edit] Products
Main article: List of Google products
Google has created services and tools for the general public and business environment alike; including Web applications, advertising networks and solutions for businesses.
[edit] Advertising
Most of Google's revenue is derived from advertising programs. For the 2006 fiscal year, the company reported $10.492 billion in total advertising revenues and only $112 million in licensing and other revenues.[36] Google AdWords allows Web advertisers to display advertisements in Google's search results and the Google Content Network, through either a cost-per-click or cost-per-view scheme. Google AdSense website owners can also display adverts on their own site, and earn money every time ads are clicked.
[edit] Applications
Google is well-known for its web search service, which is a major factor of the company's success. As of December 2006, Google is the most used search engine on the web with a 50.8% market share, ahead of Yahoo! (23.6%) and Windows Live Search (8.4%).[37] Google indexes billions of Web pages, so that users can search for the information they desire, through the use of keywords and operators. Google has also employed the Web Search technology into other search services, including Image Search, Google News, the price comparison site Google Product Search, the interactive Usenet archive Google Groups, Google Maps and more.
In 2004, Google launched its own free web-based email service, known as Gmail.[38] Gmail features spam filtering technology and the capability to use Google technology to search email. The service generates revenue by displaying advertisements from the AdWords service that are tailored to the content of the email messages displayed on screen.
In early 2006, the company launched Google Video, which not only allows users to search and view freely available videos, but also offers users and media publishers the ability to publish their content, including television shows on CBS, NBA basketball games, and music videos.[39]
Google has also developed several desktop applications, including Google Earth, an interactive mapping program powered by satellite imagery that covers the vast majority of the earth. Google Earth is generally considered to be remarkably accurate and extremely detailed. For example, some major cities (Las Vegas, NV, USA for example) have such detailed images that one can zoom in close enough to read the license plates on cars on a street. Consequently, there have been some concerns about national security implications. Specifically, some countries and militaries contend the software can be used to pinpoint with near-precision accuracy the physical location of critical infrastructure, commercial and residential buildings, bases, government agencies, and so on. However, the satellite images are not necessarily frequently updated, and all of them are available at no charge through other products and even government sources (NASA and the National Geospatial-Intelligence Agency, for example.) Some counter this argument by stating that Google Earth makes it easier to access and research the images.
Many other products are available through Google Labs, which is a collection of incomplete applications that are still being tested for use by the general public.
Google has promoted their products in various ways. In London, Google Space was set-up in Heathrow Airport, showcasing several products, including Gmail, Google Earth and Picasa.[40][41] Also, a similar page was launched for American college students, under the name College Life, Powered by Google.[42]
In 2007, some reports surfaced that Google was planning the release of its own mobile phone, possibly a competitor to Apple's iPhone.[43][44][45] The project may be a collaboration between Google and Orange, HTC, Samsung, or another manufacturer. However, very little is known about the project and most of the information available is speculation.
[edit] Enterprise products
In 2007, Google launched Google Apps Premium Edition, a software suite for businesses that provides e-mail, instant messaging, calendar, word processing, as well as a spreadsheet program.[46] This product is targeted primarily at the business user, and intended to compete directly versus Microsoft's Office suite, with a price of approximately USD50 per user per year compared to USD500 per user for Microsoft Office.[46] A large implementation of Google Apps with 38,000 users is at Lakehead University in Thunder Bay, Ontario, Canada.[47]
[edit] Platform
Main article: Google platform
Google's services are run on several server farms, each consisting of thousands of low-cost commodity computers running stripped-down versions of Linux. While the company does not provide detailed information about its hardware, a 2006 estimate consisted of over 450,000 servers, racked up in clusters located in data centers around the world.[48]
[edit] Corporate affairs and culture
A license plate seen in the Googleplex parking lot.Google is particularly known for its relaxed corporate culture, reminiscent of the Dot-com boom. In January 2007, it was cited by Fortune Magazine as the #1 (of 100) best company to work for.[49] Google's corporate philosophy is based on many casual principles including, "You can make money without doing evil", "You can be serious without a suit," and "Work should be challenging and the challenge should be fun." A complete list of corporate fundamentals is available on Google's website.[50] Google's relaxed corporate culture can also be seen externally through their holiday variations of the Google logo.
Typical salaries at Google are considered to be quite low by industry standards.[citation needed] For example, some system administrators earn no more than $35,000 per year – considered to be quite low for the Bay Area job market.[51] However, Google's stock performance following its IPO has enabled many early employees to be competitively compensated by participation in the corporation's remarkable equity growth.[52] Google implemented other employee incentives in 2005, such as the Google Founders' Award, in addition to offering higher salaries to new employees. Google's workplace amenities, culture, global popularity, and strong brand recognition have also attracted potential applicants.
After the company's IPO in August 2004, it was reported that founders Sergey Brin and Larry Page, and CEO Eric Schmidt, requested that their base salary be cut to $1.00.[53] Subsequent offers by the company to increase their salaries have been turned down, primarily because, "their primary compensation continues to come from returns on their ownership stakes in Google. As significant stockholders, their personal wealth is tied directly to sustained stock price appreciation and performance, which provides direct alignment with stockholder interests."[53] Prior to 2004, Schmidt was making $250,000 per year, and Page and Brin each earned a salary of $150,000.[53]
They have all declined recent offers of bonuses and increases in compensation by Google's board of directors. In a 2006 report of the United States' richest people, Forbes reported that Sergey Brin was #12 with a net worth of $14.1 billion, and Larry Page was #13 with a net worth of $14.0 billion.[54]
[edit] Googleplex
The GoogleplexMain article: Googleplex
As a play on Google's name, its headquarters, in Mountain View, California, is referred to as "the Googleplex" — a googolplex being 1 followed by a googol of zeros, and the HQ being a complex of buildings (cf. multiplex, cineplex, etc). The lobby is decorated with a piano, lava lamps, old server clusters, and a projection of search queries on the wall. The hallways are full of exercise balls and bicycles. Each employee has access to the corporate recreation center. Recreational amenities are scattered throughout the campus and include a workout room with weights and rowing machines, locker rooms, washers and dryers, a massage room, assorted video games, Foosball, a baby grand piano, a pool table, and ping pong. In addition to the rec room, there are snack rooms stocked with various cereals, gummy bears, toffee, licorice, cashews, yogurt, carrots, fresh fruit, and dozens of different drinks including fresh juice, soda, and make your own cappuccino.
Sign at the GoogleplexIn 2006, Google moved into 311,000 square feet of office space in New York City, at 111 Eighth Ave. in Manhattan.[55] The office was specially designed and built for Google and houses its largest advertising sales team, which has been instrumental in securing large partnerships, most recently deals with MySpace and AOL.[55] In 2003, they added an engineering staff in New York City, which has been responsible for more than 100 engineering projects, including Google Maps, Google Spreadsheets, and others.[55] It is estimated that the building costs Google $10 million per year to rent and is similar in design and functionality to its Mountain View headquarters, including Foosball, air hockey, and ping-pong tables, as well as a video game area.[55]
Google is also making steps to ensure that their operations are environmentally sound. In October 2006, the company announced plans to install thousands of solar panels to provide up to 1.6 megawatts of electricity, enough to satisfy approximately 30% of the campus' energy needs.[56] The system will be the largest solar power system constructed on a U.S. corporate campus and one of the largest on any corporate site in the world.[56] In June 2007, Google announced that they plan to become carbon neutral by 2008, which includes investing in energy efficiency, renewable energy sources, and purchasing carbon offsets, such as investing in projects like capturing and burning methane from animal waste at Mexican and Brazilian farms.[57]
[edit] "Twenty percent" time
All Google engineers are encouraged to spend 20% of their work time (one day per week) on projects that interest them. Some of Google's newer services, such as Gmail, Google News, Orkut, and AdSense originated from these independent endeavors.[58] In a talk at Stanford University, Marissa Mayer, Google's vice president of search products and user experience, stated that her analysis showed that half of the new product launches originated from the 20% time.[59]
[edit] Easter eggs and April Fool's Day jokes
Main article: Google's hoaxes
Google has a tradition of creating April Fool's Day jokes — such as Google MentalPlex, which allegedly featured the use of mental power to search the web.[60] In 2002, they claimed that pigeons were the secret behind their growing search engine.[61] In 2004, they featured Google Lunar (which claimed to feature jobs on the moon),[62] and in 2005, a fictitious brain-boosting drink, termed Google Gulp was announced.[63] In 2006, they came up with Google Romance, a hypothetical online dating service.[64] In 2007, Google announced two joke products. The first was a free wireless Internet service called TiSP (Toilet Internet Service Provider) [65] in which one obtained a connection by flushing one end of a fiber-optic cable down their toilet and waiting only an hour for a "Plumbing Hardware Dispatcher (PHD)" to connect it to the Internet.[65] Additionally, Google's Gmail page displayed an announcement for Gmail Paper, which allows users of their free email service to have email messages printed and shipped to a snail mail address.[66]
Some thought the announcement of Gmail in 2004 around April Fool's Day (as well as the doubling of Gmail's storage space to two gigabytes in 2005) was a joke, although both of these turned out to be genuine announcements. In 2005, a comedic graph depicting Google's goal of "infinity plus one" GB of storage was featured on the Gmail homepage.
Google's services contain a number of Easter eggs; for instance, the Language Tools page offers the search interface in the Swedish Chef's "Bork bork bork," Pig Latin, ”Hacker” (Actually leetspeak), Elmer Fudd, and Klingon.[67] When asked how to get from a location in the U.S. to a location in Europe, Google Maps will provide directions that include an instruction to "Swim across the Atlantic Ocean." [68] In addition, the search engine calculator provides The Answer to Life, the Universe, and Everything from Douglas Adams' The Hitchhiker's Guide to the Galaxy.[69] As Google's search box can be used as a unit converter (as well as a calculator), some non-standard units are built in, such as the Smoot. Google also routinely modifies its logo in accordance with various holidays or special events throughout the year, such as Christmas, Mother's Day, or various birthdays of notable individuals.[70]
[edit] IPO and culture
Many people speculated that Google's IPO would inevitably lead to changes in the company's culture,[71] because of shareholder pressure for employee benefit reductions and short-term advances, or because a large number of the company's employees would suddenly become millionaires on paper. In a report given to potential investors, co-founders Sergey Brin and Larry Page promised that the IPO would not change the company's culture.[72] Later Mr. Page said, "We think a lot about how to maintain our culture and the fun elements. We spent a lot of time getting our offices right. We think it's important to have a high density of people. People are packed together everywhere. We all share offices. We like this set of buildings because it's more like a densely packed university campus than a typical suburban office park."[73]
However, many analysts are finding that as Google grows the company is becoming more "corporate". In 2005, articles in The New York Times and other sources began suggesting that Google had lost its anti-corporate, no evil philosophy.[74][75] In an effort to maintain the company's unique culture, Google has designated a Chief Culture Officer in 2006, who also serves as the Director of Human Resources. The purpose of the Chief Culture Officer is to develop and maintain the culture and work on ways to keep true to the core values that the company was founded on in the beginning — a flat organization, a lack of hierarchy, a collaborative environment.[76]
[edit] Criticism
Main article: Criticism of Google
As it has grown, Google has found itself the focus of several controversies related to its business practices and services. For example, Google Book Search's effort to digitize millions of books and make the full text searchable has led to copyright disputes with the Authors Guild. Google's cooperation with the governments of China, and to a lesser extent France and Germany (regarding Holocaust denial) to filter search results in accordance to regional laws and regulations has led to claims of censorship. Google's persistent cookie and other information collection practices have led to concerns over user privacy. A number of governments have raised concerns about the security risks posed by geographic details provided by Google Earth's satellite imaging.[77] Google has also been criticized by advertisers regarding its inability to combat click fraud, when a person or automated script is used to generate a charge on an advertisement without really having an interest in the product. Industry reports in 2006 claim that approximately 14 to 20 percent of clicks were in fact fraudulent or invalid.[78]
Animal
Animal
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is missing citations and/or footnotes.
This article contains insufficiently sourced phrases. Using inline citations helps guard against copyright violations and factual inaccuracies. You may improve the article or discuss this issue on its talk page. Help on using footnotes is available. This article has been tagged since July 2007.
For other uses, see Animal (disambiguation).
“Animalia” redirects here. For the book, see Animalia (book).
AnimalsFossil range: Ediacaran - Recent
Clockwise from top-left: Loligo vulgaris (a mollusk), Chrysaora quinquecirrha (a cnidarian), Aphthona flava (an arthropod), Eunereis longissima (an annelid), and Panthera tigris (a chordate).
Scientific classification
Domain:
Eukaryota
(unranked)
Opisthokonta
Kingdom:
AnimaliaLinnaeus, 1758
Phyla
Subregnum Parazoa
Porifera
(alternatively)
Calcarea
Silicarea
Subregnum Eumetazoa
Placozoa
Radiata (unranked)
Ctenophora
Cnidaria
Trilobozoa †
Bilateria (unranked)
Orthonectida
Rhombozoa
Acoelomorpha
Chaetognatha
Superphylum Deuterostomia
Chordata
Hemichordata
Echinodermata
Xenoturbellida
Vetulicolia †
Superphylum Ecdysozoa
Kinorhyncha
Loricifera
Priapulida
Nematoda
Nematomorpha
Lobopodia †
Onychophora
Tardigrada
Arthropoda
Superphylum Platyzoa
Platyhelminthes
Gastrotricha
Rotifera
Acanthocephala
Gnathostomulida
Micrognathozoa
Cycliophora
Superphylum Lophotrochozoa
Sipuncula
Hyolitha †
Nemertea
Phoronida
Ectoprocta
Bryozoa
Entoprocta
Brachiopoda
Mollusca
Annelida
Echiura
Orange elephant ear sponge, Agelas clathrodes, in foreground. Two corals in the background: a sea fan, Iciligorgia schrammi, and a sea rod, Plexaurella nutans.
Animals are a major group of organisms, classified as the kingdom Animalia or Metazoa. In general they are multicellular, responsive to their environment, and feed by consuming other organisms or parts of them. Their body plan becomes fixed as they develop, usually early on in their development as embryos, although some undergo a process of metamorphosis later on.
The word "animal" comes from the Latin word animal, of which animalia is the plural, and is derived from anima, meaning vital breath or soul. In everyday colloquial usage, the word usually refers to non-human animals. The biological definition of the word refers to all members of the Kingdom Animalia. Therefore, when the word "animal" is used in a biological context, humans are included.
Contents[show]
1 Characteristics
1.1 Structure
1.2 Reproduction and development
2 Origin and fossil record
3 Groups of animals
3.1 Deuterostomes
3.2 Ecdysozoa
3.3 Platyzoa
3.4 Lophotrochozoa
4 Model organisms
5 History of classification
6 See also
7 References
8 External links
//
[edit] Characteristics
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and usually multicellular (although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at certain life stages. Embryos pass through a blastula stage, which is a characteristic exclusive to animals.
[edit] Structure
With a few exceptions, most notably the sponges (Phylum Porifera), animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and nerve tissue, which sends and processes signals. There is also typically an internal digestive chamber, with one or two openings. Animals with this sort of organization are called metazoans, or eumetazoans when the former is used for animals in general.
All animals have eukaryotic cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules. During development it forms a relatively flexible framework upon which cells can move about and be reorganized, making complex structures possible. In contrast, other multicellular organisms like plants and fungi have cells held in place by cell walls, and so develop by progressive growth. Also, unique to animal cells are the following intercellular junctions: tight junctions, gap junctions, and desmosomes.
[edit] Reproduction and development
Nearly all animals undergo some form of sexual reproduction. Adults are diploid or polyploid. They have a few specialized reproductive cells, which undergo meiosis to produce smaller motile spermatozoa or larger non-motile ova. These fuse to form zygotes, which develop into new individuals.
Many animals are also capable of asexual reproduction. This may take place through parthenogenesis, where fertile eggs are produced without mating, or in some cases through fragmentation.
A newt lung cell stained with fluorescent dyes undergoing mitosis, specifically early anaphase.
A zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers - an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.
Most animals grow by indirectly using the energy of sunlight. Plants use this energy to convert sunlight into simple sugars using a process known as photosynthesis. Starting with the molecules carbon dioxide (CO2) and water (H2O), photosynthesis converts the energy of sunlight into chemical energy stored in the bonds of glucose (C6H12O6) and releases oxygen (O2). These sugars are then used as the building blocks which allow the plant to grow. When animals eat these plants (or eat other animals which have eaten plants), the sugars produced by the plant are used by the animal. They are either used directly to help the animal grow, or broken down, releasing stored solar energy, and giving the animal the energy required for motion. This process is known as glycolysis.
Animals who live close to hydrothermal vents and cold seeps on the ocean floor are not dependent on the energy of sunlight. Instead, chemosynthetic archaea and eubacteria form the base of the food chain.
[edit] Origin and fossil record
Animals are generally considered to have evolved from a flagellated eukaryote. Their closest known living relatives are the choanoflagellates, collared flagellates that have a morphology similar to the choanocytes of certain sponges. Molecular studies place animals in a supergroup called the opisthokonts, which also include the choanoflagellates, fungi and a few small parasitic protists. The name comes from the posterior location of the flagellum in motile cells, such as most animal spermatozoa, whereas other eukaryotes tend to have anterior flagella.
The first fossils that might represent animals appear towards the end of the Precambrian, around 575 million years ago, and are known as the Ediacaran or Vendian biota. These are difficult to relate to later fossils, however. Some may represent precursors of modern phyla, but they may be separate groups, and it is possible they are not really animals at all. Aside from them, most known animal phyla make a more or less simultaneous appearance during the Cambrian period, about 542 million years ago. It is still disputed whether this event, called the Cambrian explosion, represents a rapid divergence between different groups or a change in conditions that made fossilization possible.
[edit] Groups of animals
The sponges (Porifera) diverged from other animals early. As mentioned above, they lack the complex organization found in most other phyla. Their cells are differentiated, but in most cases not organized into distinct tissues. Sponges are sessile and typically feed by drawing in water through pores. Archaeocyatha, which have fused skeletons, may represent sponges or a separate phylum.
Among the eumetazoan phyla, two are radially symmetric and have digestive chambers with a single opening, which serves as both the mouth and the anus. These are the Cnidaria, which include sea anemones, corals, and jellyfish, and the Ctenophora or comb jellies. Both have distinct tissues, but they are not organized into organs. There are only two main germ layers, the ectoderm and endoderm, with only scattered cells between them. As such, these animals are sometimes called diploblastic. The tiny Placozoans are similar, but they do not have a permanent digestive chamber.
The remaining animals form a monophyletic group called the Bilateria. For the most part, they are bilaterally symmetric, and often have a specialized head with feeding and sensory organs. The body is triploblastic, i.e. all three germ layers are well-developed, and tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and there is also an internal body cavity called a coelom or pseudocoelom. There are exceptions to each of these characteristics, however - for instance adult echinoderms are radially symmetric, and certain parasitic worms have extremely simplified body structures.
Genetic studies have considerably changed our understanding of the relationships within the Bilateria. Most appear to belong to four major lineages:
Deuterostomes
Ecdysozoa
Platyzoa
Lophotrochozoa
In addition to these, there are a few small groups of bilaterians with relatively similar structure that appear to have diverged before these major groups. These include the Acoelomorpha, Rhombozoa, and Orthonectida. The Myxozoa, single-celled parasites that were originally considered Protozoa, are now believed to have developed from the Bilateria as well.
[edit] Deuterostomes
White's Tree Frog, Litoria caerulea.
Deuterostomes differ from the other Bilateria, called protostomes, in several ways. In both cases there is a complete digestive tract. However, in protostomes the initial opening (the archenteron) develops into the mouth, and an anus forms separately. In deuterostomes this is reversed. In most protostomes cells simply fill in the interior of the gastrula to form the mesoderm, called schizocoelous development, but in deuterostomes it forms through invagination of the endoderm, called enterocoelic pouching. Deuterostomes also have a dorsal, rather than a ventral, nerve chord and their embryos undergo different cleavage.
All this suggests the deuterostomes and protostomes are separate, monophyletic lineages. The main phyla of deuterostomes are the Echinodermata and Chordata. The former are radially symmetric and exclusively marine, such as starfish, sea urchins, and sea cucumbers. The latter are dominated by the vertebrates, animals with backbones. These include fish, amphibians, reptiles, birds, and mammals.
In addition to these, the deuterostomes also include the Hemichordata or acorn worms. Although they are not especially prominent today, the important fossil graptolites may belong to this group.
The Chaetognatha or arrow worms may also be deuterostomes, but more recent studies suggest protostome affinities.
[edit] Ecdysozoa
Yellow-winged Darter, Sympetrum flaveolum
The Ecdysozoa are protostomes, named after the common trait of growth by moulting or ecdysis. The largest animal phylum belongs here, the Arthropoda, including insects, spiders, crabs, and their kin. All these organisms have a body divided into repeating segments, typically with paired appendages. Two smaller phyla, the Onychophora and Tardigrada, are close relatives of the arthropods and share these traits.
The ecdysozoans also include the Nematoda or roundworms, the second largest animal phylum. Roundworms are typically microscopic, and occur in nearly every environment where there is water. A number are important parasites. Smaller phyla related to them are the Nematomorpha or horsehair worms, which are invisible to the unaided eye, and the Kinorhyncha, Priapulida, and Loricifera. These groups have a reduced coelom, called a pseudocoelom.
The remaining two groups of protostomes are sometimes grouped together as the Spiralia, since in both embryos develop with spiral cleavage.
[edit] Platyzoa
Bedford's flatworm, Pseudobiceros bedfordi
The Platyzoa include the phylum Platyhelminthes, the flatworms. These were originally considered some of the most primitive Bilateria, but it now appears they developed from more complex ancestors.
A number of parasites are included in this group, such as the flukes and tapeworms. Flatworms lack a coelom, as do their closest relatives, the microscopic Gastrotricha.
The other platyzoan phyla are microscopic and pseudocoelomate. The most prominent are the Rotifera or rotifers, which are common in aqueous environments. They also include the Acanthocephala or spiny-headed worms, the Gnathostomulida, Micrognathozoa, and possibly the Cycliophora. These groups share the presence of complex jaws, from which they are called the Gnathifera.
[edit] Lophotrochozoa
Big blue octopus, Octopus cyanea
The Lophotrochozoa include two of the most successful animal phyla, the Mollusca and Annelida. The former includes animals such as snails, clams, and squids, and the latter comprises the segmented worms, such as earthworms and leeches. These two groups have long been considered close relatives because of the common presence of trochophore larvae, but the annelids were considered closer to the arthropods, because they are both segmented. Now this is generally considered convergent evolution, owing to many morphological and genetic differences between the two phyla.
The Lophotrochozoa also include the Nemertea or ribbon worms, the Sipuncula, and several phyla that have a fan of cilia around the mouth, called a lophophore. These were traditionally grouped together as the lophophorates, but it now appears they are paraphyletic, some closer to the Nemertea and some to the Mollusca and Annelida. They include the Brachiopoda or lamp shells, which are prominent in the fossil record, the Entoprocta, the Phoronida, and possibly the Bryozoa or moss animals.
[edit] Model organisms
Because of the great diversity found in animals, it is more economical for scientists around the world concert their efforts on a small number of chosen species so that connections can be drawn from their work and conclusions extrapolated about how animals function in general. Because they are easy to keep and breed, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans have long been the most intensively studied metazoan model organism, and among the first lifeforms to be genetically sequenced. This was facilitated by the severely reduced state of their genomes, but the double-edged sword here is that with many genes, introns and linkages lost, these ecdysozoans can teach us little about the origins of animals in general. The extent of this type of evolution within the superphylum will be revealed by the crustacean, annelid, and molluscan genome projects currently in progress. Analysis of the starlet sea anemone genome has emphasised the importance of sponges, placozoans, and choanoflagellates, also being sequenced, in explaining the arrival of 1500 ancestral genes unique to the Eumetazoa.[1]
[edit] History of classification
Carolus Linnaeus, known as the "father of modern taxonomy".
Aristotle divided the living world between animals and plants, and this was followed by Carolus Linnaeus in the first hierarchical classification. Since then biologists have begun emphasizing evolutionary relationships, and so these groups have been restricted somewhat. For instance, microscopic protozoa were originally considered animals because they move, but are now treated separately.
In Linnaeus' original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, the Chordata, whereas the various other forms have been separated out. The above lists represent our current understanding of the group, though there is some variation from source to source.
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is missing citations and/or footnotes.
This article contains insufficiently sourced phrases. Using inline citations helps guard against copyright violations and factual inaccuracies. You may improve the article or discuss this issue on its talk page. Help on using footnotes is available. This article has been tagged since July 2007.
For other uses, see Animal (disambiguation).
“Animalia” redirects here. For the book, see Animalia (book).
AnimalsFossil range: Ediacaran - Recent
Clockwise from top-left: Loligo vulgaris (a mollusk), Chrysaora quinquecirrha (a cnidarian), Aphthona flava (an arthropod), Eunereis longissima (an annelid), and Panthera tigris (a chordate).
Scientific classification
Domain:
Eukaryota
(unranked)
Opisthokonta
Kingdom:
AnimaliaLinnaeus, 1758
Phyla
Subregnum Parazoa
Porifera
(alternatively)
Calcarea
Silicarea
Subregnum Eumetazoa
Placozoa
Radiata (unranked)
Ctenophora
Cnidaria
Trilobozoa †
Bilateria (unranked)
Orthonectida
Rhombozoa
Acoelomorpha
Chaetognatha
Superphylum Deuterostomia
Chordata
Hemichordata
Echinodermata
Xenoturbellida
Vetulicolia †
Superphylum Ecdysozoa
Kinorhyncha
Loricifera
Priapulida
Nematoda
Nematomorpha
Lobopodia †
Onychophora
Tardigrada
Arthropoda
Superphylum Platyzoa
Platyhelminthes
Gastrotricha
Rotifera
Acanthocephala
Gnathostomulida
Micrognathozoa
Cycliophora
Superphylum Lophotrochozoa
Sipuncula
Hyolitha †
Nemertea
Phoronida
Ectoprocta
Bryozoa
Entoprocta
Brachiopoda
Mollusca
Annelida
Echiura
Orange elephant ear sponge, Agelas clathrodes, in foreground. Two corals in the background: a sea fan, Iciligorgia schrammi, and a sea rod, Plexaurella nutans.
Animals are a major group of organisms, classified as the kingdom Animalia or Metazoa. In general they are multicellular, responsive to their environment, and feed by consuming other organisms or parts of them. Their body plan becomes fixed as they develop, usually early on in their development as embryos, although some undergo a process of metamorphosis later on.
The word "animal" comes from the Latin word animal, of which animalia is the plural, and is derived from anima, meaning vital breath or soul. In everyday colloquial usage, the word usually refers to non-human animals. The biological definition of the word refers to all members of the Kingdom Animalia. Therefore, when the word "animal" is used in a biological context, humans are included.
Contents[show]
1 Characteristics
1.1 Structure
1.2 Reproduction and development
2 Origin and fossil record
3 Groups of animals
3.1 Deuterostomes
3.2 Ecdysozoa
3.3 Platyzoa
3.4 Lophotrochozoa
4 Model organisms
5 History of classification
6 See also
7 References
8 External links
//
[edit] Characteristics
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and usually multicellular (although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at certain life stages. Embryos pass through a blastula stage, which is a characteristic exclusive to animals.
[edit] Structure
With a few exceptions, most notably the sponges (Phylum Porifera), animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and nerve tissue, which sends and processes signals. There is also typically an internal digestive chamber, with one or two openings. Animals with this sort of organization are called metazoans, or eumetazoans when the former is used for animals in general.
All animals have eukaryotic cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules. During development it forms a relatively flexible framework upon which cells can move about and be reorganized, making complex structures possible. In contrast, other multicellular organisms like plants and fungi have cells held in place by cell walls, and so develop by progressive growth. Also, unique to animal cells are the following intercellular junctions: tight junctions, gap junctions, and desmosomes.
[edit] Reproduction and development
Nearly all animals undergo some form of sexual reproduction. Adults are diploid or polyploid. They have a few specialized reproductive cells, which undergo meiosis to produce smaller motile spermatozoa or larger non-motile ova. These fuse to form zygotes, which develop into new individuals.
Many animals are also capable of asexual reproduction. This may take place through parthenogenesis, where fertile eggs are produced without mating, or in some cases through fragmentation.
A newt lung cell stained with fluorescent dyes undergoing mitosis, specifically early anaphase.
A zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers - an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.
Most animals grow by indirectly using the energy of sunlight. Plants use this energy to convert sunlight into simple sugars using a process known as photosynthesis. Starting with the molecules carbon dioxide (CO2) and water (H2O), photosynthesis converts the energy of sunlight into chemical energy stored in the bonds of glucose (C6H12O6) and releases oxygen (O2). These sugars are then used as the building blocks which allow the plant to grow. When animals eat these plants (or eat other animals which have eaten plants), the sugars produced by the plant are used by the animal. They are either used directly to help the animal grow, or broken down, releasing stored solar energy, and giving the animal the energy required for motion. This process is known as glycolysis.
Animals who live close to hydrothermal vents and cold seeps on the ocean floor are not dependent on the energy of sunlight. Instead, chemosynthetic archaea and eubacteria form the base of the food chain.
[edit] Origin and fossil record
Animals are generally considered to have evolved from a flagellated eukaryote. Their closest known living relatives are the choanoflagellates, collared flagellates that have a morphology similar to the choanocytes of certain sponges. Molecular studies place animals in a supergroup called the opisthokonts, which also include the choanoflagellates, fungi and a few small parasitic protists. The name comes from the posterior location of the flagellum in motile cells, such as most animal spermatozoa, whereas other eukaryotes tend to have anterior flagella.
The first fossils that might represent animals appear towards the end of the Precambrian, around 575 million years ago, and are known as the Ediacaran or Vendian biota. These are difficult to relate to later fossils, however. Some may represent precursors of modern phyla, but they may be separate groups, and it is possible they are not really animals at all. Aside from them, most known animal phyla make a more or less simultaneous appearance during the Cambrian period, about 542 million years ago. It is still disputed whether this event, called the Cambrian explosion, represents a rapid divergence between different groups or a change in conditions that made fossilization possible.
[edit] Groups of animals
The sponges (Porifera) diverged from other animals early. As mentioned above, they lack the complex organization found in most other phyla. Their cells are differentiated, but in most cases not organized into distinct tissues. Sponges are sessile and typically feed by drawing in water through pores. Archaeocyatha, which have fused skeletons, may represent sponges or a separate phylum.
Among the eumetazoan phyla, two are radially symmetric and have digestive chambers with a single opening, which serves as both the mouth and the anus. These are the Cnidaria, which include sea anemones, corals, and jellyfish, and the Ctenophora or comb jellies. Both have distinct tissues, but they are not organized into organs. There are only two main germ layers, the ectoderm and endoderm, with only scattered cells between them. As such, these animals are sometimes called diploblastic. The tiny Placozoans are similar, but they do not have a permanent digestive chamber.
The remaining animals form a monophyletic group called the Bilateria. For the most part, they are bilaterally symmetric, and often have a specialized head with feeding and sensory organs. The body is triploblastic, i.e. all three germ layers are well-developed, and tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and there is also an internal body cavity called a coelom or pseudocoelom. There are exceptions to each of these characteristics, however - for instance adult echinoderms are radially symmetric, and certain parasitic worms have extremely simplified body structures.
Genetic studies have considerably changed our understanding of the relationships within the Bilateria. Most appear to belong to four major lineages:
Deuterostomes
Ecdysozoa
Platyzoa
Lophotrochozoa
In addition to these, there are a few small groups of bilaterians with relatively similar structure that appear to have diverged before these major groups. These include the Acoelomorpha, Rhombozoa, and Orthonectida. The Myxozoa, single-celled parasites that were originally considered Protozoa, are now believed to have developed from the Bilateria as well.
[edit] Deuterostomes
White's Tree Frog, Litoria caerulea.
Deuterostomes differ from the other Bilateria, called protostomes, in several ways. In both cases there is a complete digestive tract. However, in protostomes the initial opening (the archenteron) develops into the mouth, and an anus forms separately. In deuterostomes this is reversed. In most protostomes cells simply fill in the interior of the gastrula to form the mesoderm, called schizocoelous development, but in deuterostomes it forms through invagination of the endoderm, called enterocoelic pouching. Deuterostomes also have a dorsal, rather than a ventral, nerve chord and their embryos undergo different cleavage.
All this suggests the deuterostomes and protostomes are separate, monophyletic lineages. The main phyla of deuterostomes are the Echinodermata and Chordata. The former are radially symmetric and exclusively marine, such as starfish, sea urchins, and sea cucumbers. The latter are dominated by the vertebrates, animals with backbones. These include fish, amphibians, reptiles, birds, and mammals.
In addition to these, the deuterostomes also include the Hemichordata or acorn worms. Although they are not especially prominent today, the important fossil graptolites may belong to this group.
The Chaetognatha or arrow worms may also be deuterostomes, but more recent studies suggest protostome affinities.
[edit] Ecdysozoa
Yellow-winged Darter, Sympetrum flaveolum
The Ecdysozoa are protostomes, named after the common trait of growth by moulting or ecdysis. The largest animal phylum belongs here, the Arthropoda, including insects, spiders, crabs, and their kin. All these organisms have a body divided into repeating segments, typically with paired appendages. Two smaller phyla, the Onychophora and Tardigrada, are close relatives of the arthropods and share these traits.
The ecdysozoans also include the Nematoda or roundworms, the second largest animal phylum. Roundworms are typically microscopic, and occur in nearly every environment where there is water. A number are important parasites. Smaller phyla related to them are the Nematomorpha or horsehair worms, which are invisible to the unaided eye, and the Kinorhyncha, Priapulida, and Loricifera. These groups have a reduced coelom, called a pseudocoelom.
The remaining two groups of protostomes are sometimes grouped together as the Spiralia, since in both embryos develop with spiral cleavage.
[edit] Platyzoa
Bedford's flatworm, Pseudobiceros bedfordi
The Platyzoa include the phylum Platyhelminthes, the flatworms. These were originally considered some of the most primitive Bilateria, but it now appears they developed from more complex ancestors.
A number of parasites are included in this group, such as the flukes and tapeworms. Flatworms lack a coelom, as do their closest relatives, the microscopic Gastrotricha.
The other platyzoan phyla are microscopic and pseudocoelomate. The most prominent are the Rotifera or rotifers, which are common in aqueous environments. They also include the Acanthocephala or spiny-headed worms, the Gnathostomulida, Micrognathozoa, and possibly the Cycliophora. These groups share the presence of complex jaws, from which they are called the Gnathifera.
[edit] Lophotrochozoa
Big blue octopus, Octopus cyanea
The Lophotrochozoa include two of the most successful animal phyla, the Mollusca and Annelida. The former includes animals such as snails, clams, and squids, and the latter comprises the segmented worms, such as earthworms and leeches. These two groups have long been considered close relatives because of the common presence of trochophore larvae, but the annelids were considered closer to the arthropods, because they are both segmented. Now this is generally considered convergent evolution, owing to many morphological and genetic differences between the two phyla.
The Lophotrochozoa also include the Nemertea or ribbon worms, the Sipuncula, and several phyla that have a fan of cilia around the mouth, called a lophophore. These were traditionally grouped together as the lophophorates, but it now appears they are paraphyletic, some closer to the Nemertea and some to the Mollusca and Annelida. They include the Brachiopoda or lamp shells, which are prominent in the fossil record, the Entoprocta, the Phoronida, and possibly the Bryozoa or moss animals.
[edit] Model organisms
Because of the great diversity found in animals, it is more economical for scientists around the world concert their efforts on a small number of chosen species so that connections can be drawn from their work and conclusions extrapolated about how animals function in general. Because they are easy to keep and breed, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans have long been the most intensively studied metazoan model organism, and among the first lifeforms to be genetically sequenced. This was facilitated by the severely reduced state of their genomes, but the double-edged sword here is that with many genes, introns and linkages lost, these ecdysozoans can teach us little about the origins of animals in general. The extent of this type of evolution within the superphylum will be revealed by the crustacean, annelid, and molluscan genome projects currently in progress. Analysis of the starlet sea anemone genome has emphasised the importance of sponges, placozoans, and choanoflagellates, also being sequenced, in explaining the arrival of 1500 ancestral genes unique to the Eumetazoa.[1]
[edit] History of classification
Carolus Linnaeus, known as the "father of modern taxonomy".
Aristotle divided the living world between animals and plants, and this was followed by Carolus Linnaeus in the first hierarchical classification. Since then biologists have begun emphasizing evolutionary relationships, and so these groups have been restricted somewhat. For instance, microscopic protozoa were originally considered animals because they move, but are now treated separately.
In Linnaeus' original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, the Chordata, whereas the various other forms have been separated out. The above lists represent our current understanding of the group, though there is some variation from source to source.
Human
Human
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is about modern humans. For other human species, see Homo (genus). For other uses, see Human (disambiguation).
HumanFossil range: Pleistocene - Recent
Image of a man and a woman on the Pioneer plaque.
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Primates
Family:
Hominidae
Genus:
Homo
Species:
H. sapiens
Subspecies:
H. s. sapiens
Trinomial name
Homo sapiens sapiensLinnaeus, 1758
Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: "wise man" or "knowing man") in the family Hominidae (the great apes).[1][2] Humans have a highly developed brain capable of abstract reasoning, language, and introspection. This mental capability, combined with an erect body carriage that frees their upper limbs for manipulating objects, has allowed humans to make far greater use of tools than any other species. Humans originated in Africa about 200,000 years ago, but they now inhabit every continent, with a total population of over 6.6 billion as of 2007[3].
Like most primates, humans are social by nature; however, humans are particularly adept at utilizing systems of communication for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of cooperating and competing groups, ranging in scale from small families and partnerships to species-wide political, scientific and economic unions. Social interactions between humans have also established an extremely wide variety of traditions, rituals, ethics, values, social norms, and laws which form the basis of human society. Humans also have a marked appreciation for beauty and aesthetics which, combined with the human desire for self-expression, has led to cultural innovations such as art, literature and music.
Humans are also noted for their desire to understand and influence the world around them, seeking to explain and manipulate natural phenomena through science, philosophy, mythology and religion. This natural curiosity has led to the development of advanced tools and skills; humans are the only known species to build fires, cook their food, clothe themselves, and use numerous other technologies.
Contents[show]
1 History
1.1 Evolution
1.2 Rise of civilization
1.3 Habitat and population
2 Biology
2.1 Physiology and genetics
2.2 Life cycle
2.3 Diet
3 Psychology
3.1 Consciousness and thought
3.2 Motivation and emotion
3.3 Love and sexuality
4 Culture
4.1 Language
4.2 Art, music and literature
4.3 Spirituality and religion
4.4 Philosophy and self-reflection
4.5 Science and technology
4.6 Race and ethnicity
5 Society
5.1 Government and politics
5.2 War
5.3 Trade and economics
6 Effect on ecosystems
7 See also
8 References
9 External links
//
History
Evolution
For more details on this topic, see Human evolution.
Reconstructed skull of Peking Man, a representative of the extinct species believed to be the nearest ancestor of Homo sapiens, Homo erectus.
The scientific study of human evolution encompasses the development of the genus Homo, but usually involves studying other hominids and hominines as well, such as Australopithecus. "Modern humans" are defined as the Homo sapiens species, of which the only extant subspecies is Homo sapiens sapiens; Homo sapiens idaltu (roughly translated as "elder wise man"), the other known subspecies, is extinct.[4] Anatomically modern humans appear in the fossil record in Africa about 130,000 years ago.[5][6]
The closest living relatives of Homo sapiens are the two species of chimpanzee: the Bonobo (Pan paniscus) and the Common Chimpanzee (Pan troglodytes). These species are equally close (they share the same common ancestor), the main difference between them is the social organization: matriarchal for the Bonobo and patriarchal for the Common Chimpanzee. Full genome sequencing resulted in the conclusion that "after 6.5 million years of separate evolution, the differences between bonobo/chimpanzee and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice". In fact, 98.4% of the DNA sequence is identical between the two Pan species and human.[7][8][9][10] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from gorillas about eight million years ago. However, a hominid skull discovered in Chad in 2001, classified as Sahelanthropus tchadensis, is approximately seven million years old, which may indicate an earlier divergence.[11]
There are two prominent scientific theories of the origins of contemporary humans. They concern the relationship between modern humans and other hominids. The single-origin, or "out-of-Africa", hypothesis proposes that modern humans evolved in Africa and later migrated outwards to replace hominids in other parts of the world. The multiregional hypothesis, on the other hand, proposes that modern humans evolved, at least in part, from independent hominid populations.[12]
Geneticists Lynn Jorde and Henry Harpending of the University of Utah proposed that the variation in human DNA is minute compared to that of other species, and that during the Late Pleistocene, the human population was reduced to a small number of breeding pairs — no more than 10,000 and possibly as few as 1,000 — resulting in a very small residual gene pool. Various reasons for this hypothetical bottleneck have been postulated, the most popular[citation needed] being the Toba catastrophe theory.
Human evolution is characterized by a number of important physiological trends, including the expansion of the brain cavity and brain itself, which is typically 1,400 cm³ in volume, over twice that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning and language acquisition in juvenile humans. Physical anthropologists argue that a reorganization of the structure of the brain is more important than cranial expansion itself. Other significant evolutionary changes included a reduction of the canine tooth, development of bipedal locomotion, and the descent of the larynx and hyoid bone, making speech possible. How these trends are related and what their role is in the evolution of complex social organization and culture are matters of ongoing debate.[13][14]
Rise of civilization
The rise of agriculture led to the foundation of stable human settlements.
For more details on this topic, see History of the world.
The most widely accepted view among current anthropologists is that Homo sapiens originated in the African savanna around 200,000 BP (Before Present), descending from Homo erectus, had colonized Eurasia and Oceania by 40,000 BP, and finally colonized the Americas approximately 10,000 years ago.[15] They displaced Homo neanderthalensis and other species descended from Homo erectus (which had colonized Eurasia as early as 2 million years ago) through more successful reproduction and competition for resources.
The earliest humans were hunter-gatherers, a lifestyle well-suited to the savanna. They generally lived in small, nomadic groups. Around 10,000 years ago, the advent of agriculture prompted the Neolithic Revolution. Access to a stable food source led to the formation of permanent human settlements, the domestication of animals, and the use of metal tools. Agriculture also encouraged trade and cooperation, leading to complex societies. Villages developed into thriving civilizations in regions such as the Middle East's Fertile Crescent.
Around 6,000 years ago, the first proto-states developed in Mesopotamia, Egypt and the Indus Valley. Military forces were formed for protection, and government bureaucracies for administration. States cooperated and competed for resources, in some cases waging wars. Around 2,000 – 3,000 years ago, some states, such as Persia, China, and Rome, developed through conquest into the first expansive empires. Influential religions, such as the Abrahamic and Dharmic religions, also rose to prominence at this time.
The late Middle Ages saw the rise of revolutionary ideas and technologies. In China, an advanced and urbanized economy promoted innovations such as printing and the compass, while the Islamic Golden Age saw major scientific advancements in Muslim empires. In Europe, the rediscovery of classical learning and inventions such as the printing press led to the Renaissance in the 14th century. Over the next 500 years, exploration and imperialistic conquest brought much of the Americas, Asia, and Africa under European control, leading to later struggles for independence. The Scientific Revolution in the 17th century and the Industrial Revolution in the 18th – 19th centuries promoted major innovations in transport, such as the railway and automobile; energy development, such as coal and electricity; and government, such as representative democracy and Communism.
As a result of such changes, modern humans live in a world that has become increasingly globalized and interconnected. Although this has encouraged the growth of science, art, and technology, it has also led to culture clashes, the development and use of weapons of mass destruction, and increased environmental destruction and pollution.
Habitat and population
For more details on this topic, see Demography and World population.
Early human settlements were dependent on proximity to water and, depending on the lifestyle, other natural resources, such as fertile land for growing crops and grazing livestock, or seasonally by hunting populations of prey. However, humans have a great capacity for altering their habitats by various methods, such as through irrigation, urban planning, construction, transport, and manufacturing goods, and with the advent of large-scale trade and transport infrastructure, proximity to these resources has become unnecessary, and in many places these factors are no longer a driving force behind the growth and decline of a population. Nonetheless, the manner in which a habitat is altered is often a major determinant in population change.
Technology has allowed humans to colonize all of the continents and adapt to all climates. Within the last few decades, humans have explored Antarctica, the ocean depths, and space, although long-term habitation of these environments is not yet possible. With a population of over six billion, humans are among the most numerous of the large mammals. Most humans (61%) live in Asia. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 0.5% in Oceania. (See list of countries by population and list of countries by population density.)
Human habitation within closed ecological systems in hostile environments, such as Antarctica and outer space, is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with no more than thirteen humans in space at any given time. Between 1969 and 1972, two humans at a time spent brief intervals on the Moon. As of 2007, no other celestial body has been visited by human beings, although there has been a continuous human presence in outer space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000.
From AD 1800 to 2000, the human population increased from one billion to six billion. In 2004, around 2.5 billion out of 6.3 billion people (39.7%) lived in urban areas, and this percentage is expected to rise throughout the 21st century. Problems for humans living in cities include various forms of pollution and crime,[16] especially in inner city and suburban slums. Benefits of urban living include increased literacy, access to the global canon of human knowledge and decreased susceptibility to rural famines.
Humans have had a dramatic effect on the environment. It has been hypothesized that in the past, human predation has contributed to the extinction of a number of species; as humans are not generally preyed on themselves, humans have been described as the ultimate superpredators.[17] Currently, through land development and pollution, humans are thought to be the main contributor to global climate change.[18] This is believed to be a major contributor to the ongoing Holocene extinction event, a mass extinction which, if it continues at its current rate, is predicted to wipe out half of all species over the next century.[19][20]
Biology
For more details on this topic, see Human biology.
Physiology and genetics
For more details on this topic, see Human anatomy, Human physical appearance, and Human genetics.
An old diagram of a male human skeleton.
Human body types vary substantially. Although body size is largely determined by genes, it is also significantly influenced by environmental factors such as diet and exercise. The average height of an adult human is about 5 to 6 feet (1.5 to 1.8 m) tall, although this varies significantly from place to place.[21][22] Humans are capable of fully bipedal locomotion, thus leaving their arms available for manipulating objects using their hands, aided especially by opposable thumbs. As human physiology has not fully adapted to bipedalism, the pelvic region and vertebral column tend to become worn, causing the elderly to have difficulty in walking.[citation needed]
Although humans appear relatively hairless compared to other primates, with notable hair growth occurring chiefly on the top of the head, underarms and pubic area, the average human has more hair follicles on his or her body than the average chimpanzee. The main distinction is that human hairs are shorter, finer, and less heavily pigmented than the average chimpanzee's, thus making them harder to see.[23]
An Inuit woman, circa 1907.
The hue of human hair and skin is determined by the presence of pigments called melanins. Human skin hues can range from very dark brown to very pale pink, while human hair ranges from blond to brown to red to, most commonly, black.[24] Most researchers believe that skin darkening was an adaptation that evolved as a protection against ultraviolet solar radiation, as melanin is an effective sun-block.[25] The skin pigmentation of contemporary humans is geographically stratified, and in general correlates with the level of ultraviolet radiation. Human skin also has a capacity to darken (sun tanning) in response to exposure to ultraviolet radiation.[26][27]
The average sleep requirement is between seven and eight hours a day for an adult and nine to ten hours for a child; elderly people usually sleep for six to seven hours. Experiencing less sleep than this is common in modern societies; this sleep deprivation can lead to negative effects. A sustained restriction of adult sleep to four hours per day has been shown to correlate with changes in physiology and mental state, including fatigue, aggression, and bodily discomfort.
Humans are an eukaryotic species. Each diploid cell has two sets of 23 chromosomes, each set received from one parent. There are 22 pairs of autosomes and one pair of sex chromosomes. By present estimates, humans have approximately 20,000 – 25,000 genes. Like other mammals, humans have an XY sex-determination system, so that females have the sex chromosomes XX and males have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes, such as hemophilia, affect men more often than women.
Human embryo at 5 weeks.
Life cycle
The human life cycle is similar to that of other placental mammals. New humans develop viviparously from conception. An egg is usually fertilized inside the female by sperm from the male through sexual intercourse, though the recent technology of in vitro fertilization is occasionally used. The fertilized egg, called a zygote, divides inside the female's uterus to become an embryo, which over a period of thirty-eight weeks (9 months) of gestation becomes a human fetus. After this span of time, the fully-grown fetus is expelled from the female's body and breathes independently as an infant for the first time. At this point, most modern cultures recognize the baby as a person entitled to the full protection of the law, though some jurisdictions extend personhood to human fetuses while they remain in the uterus.
Two young human girls.
Compared with that of other species, human childbirth is dangerous. Painful labors lasting twenty-four hours or more are not uncommon, and may result in injury, or even death, to the child or mother. This is because of both the relatively large fetal head circumference (for housing the brain) and the mother's relatively narrow pelvis (a trait required for successful bipedalism, by way of natural selection).[28][29] The chances of a successful labor increased significantly during the 20th century in wealthier countries with the advent of new medical technologies. In contrast, pregnancy and natural childbirth remain relatively hazardous ordeals in developing regions of the world, with maternal death rates approximately 100 times more common than in developed countries.[30]
In developed countries, infants are typically 3 – 4 kg (6 – 9 pounds) in weight and 50 – 60 cm (20 – 24 inches) in height at birth.[31] However, low birth weight is common in developing countries, and contributes to the high levels of infant mortality in these regions.[32] Helpless at birth, humans continue to grow for some years, typically reaching sexual maturity at 12 to 15 years of age. Human girls continue to grow physically until around the age of 18, and human boys until around age 21. The human life span can be split into a number of stages: infancy, childhood, adolescence, young adulthood, adulthood and old age. The lengths of these stages, however — particularly the later ones — are not fixed.
There are striking differences in life expectancy around the world. The developed world is quickly getting older, with the median age around 40 years (highest in Monaco at 45.1 years), while in the developing world, the median age is 15 – 20 years (lowest in Uganda at 14.8 years). Life expectancy at birth in Hong Kong, China is 84.8 years for a female and 78.9 for a male, while in Swaziland, primarily because of AIDS, it is 31.3 years for both sexes.[33] While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older.[34]
The number of centenarians (humans of age 100 years or older) in the world was estimated by the United Nations at 210,000 in 2002.[35] At least one person, Jeanne Calment, is known to have reached the age of 122 years; higher ages have been claimed but they are not well substantiated. Worldwide, there are 81 men aged 60 or older for every 100 women of that age group, and among the oldest, there are 53 men for every 100 women.
The philosophical questions of when human personhood begins and whether it persists after death are the subject of considerable debate. The prospect of death causes unease or fear for most humans. Burial ceremonies are characteristic of human societies, often inspired by beliefs in an afterlife or immortality.
Diet
Early Homo sapiens employed a "hunter-gatherer" method as their primary means of food collection, involving combining stationary plant and fungal food sources (such as fruits, grains, tubers, and mushrooms) with wild game which must be hunted and killed in order to be consumed. It is believed that humans have used fire to prepare and cook food prior to eating since the time of their divergence from Homo erectus.
Humans are omnivorous, capable of consuming both plant and animal products. The view of humans as omnivores is supported by the evidence that both a pure animal and a pure vegetable diet can lead to deficiency diseases in humans[citation needed]. A pure animal diet can, for instance, lead to scurvy, while a pure vegetarian diet can lead to deficiency of a number of nutrients, including Vitamin B12. Supplementation, particularly for vitamin B12, is highly recommended for people living on a pure vegetable diet[36]. Some humans have chosen to abstain from eating some or all meat for religious, ethical, ecological, or health reasons.
The human diet is prominently reflected in human culture, and has led to the development of food science. In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. Lack of food remains a serious problem, with about 300,000 people starving to death every year.[37] Childhood malnutrition is also common and contributes to the global burden of disease.[38] However global food distribution is not even, and obesity among some human populations has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed, and a few developing countries. The United States Center for Disease Control states that 32% of American adults over the age of 20 are obese, while 66.5% are obese or overweight. Obesity is caused by consuming more calories than are expended, with many attributing excessive weight gain to a combination of overeating and insufficient exercise.
At least ten thousand years ago, humans developed agriculture,[39] which has substantially altered the kind of food people eat. This has led to increased populations, the development of cities, and because of increased population density, the wider spread of infectious diseases. The types of food consumed, and the way in which they are prepared, has varied widely by time, location, and culture.
Psychology
A sketch of the human brain, imposed upon the profile of Michelangelo's David - sketch by artist Priyan Weerappuli.
For more details on this topic, see Human brain and Mind.
The human brain is the center of the central nervous system in humans, as well as the primary control center for the peripheral nervous system. The brain controls "lower", or involuntary, autonomic activities such as the respiration, and digestion. The brain also controls "higher" order, conscious activities, such as thought, reasoning, and abstraction.[40] These cognitive processes constitute the mind, and, along with their behavioral consequences, are studied in the field of psychology.
The human brain is generally regarded as more capable of these higher order activities, and more "intelligent" in general, than that of any other species.[citation needed] While other animals are capable of creating structures and using simple tools — mostly as a result of instinct and learning through mimicry — human technology is vastly more complex, constantly evolving and improving with time.[citation needed] Even the most ancient human tools and structures are far more advanced than any structure or tool created by any other animal.[41]
Modern Anthropology has tended to bear out Darwin's proposition that "the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind".[42]
Consciousness and thought
For more details on this topic, see Consciousness and Cognition.
The human ability to think abstractly may be unparalleled in the animal kingdom. Humans are one of only six species to pass the mirror test — which tests whether an animal recognizes its reflection as an image of itself — along with chimpanzees, orangutans, dolphins, and possibly pigeons. In October 2006, three elephants at the Bronx Zoo also passed this test.[43] Humans under the age of 2 typically fail this test.[44] However, this may be a matter of degree rather than a sharp divide. Monkeys have been trained to apply abstract rules in tasks.[45]
The brain perceives the external world through the senses, and each individual human is influenced greatly by his or her experiences, leading to subjective views of existence and the passage of time.
Humans are variously said to possess consciousness, self-awareness, and a mind, which correspond roughly to the mental processes of thought. These are said to possess qualities such as self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. The extent to which the mind constructs or experiences the outer world is a matter of debate, as are the definitions and validity of many of the terms used above. The philosopher of cognitive science Daniel Dennett, for example, argues that there is no such thing as a narrative centre called the "mind", but that instead there is simply a collection of sensory inputs and outputs: different kinds of "software" running in parallel.[46]
Humans study the more physical aspects of the mind and brain, and by extension of the nervous system, in the field of neurology, the more behavioral in the field of psychology, and a sometimes loosely-defined area between in the field of psychiatry, which treats mental illness and behavioral disorders. Psychology does not necessarily refer to the brain or nervous system, and can be framed purely in terms of phenomenological or information processing theories of the mind. Increasingly, however, an understanding of brain functions is being included in psychological theory and practice, particularly in areas such as artificial intelligence, neuropsychology, and cognitive neuroscience.
The nature of thought is central to psychology and related fields. Cognitive psychology studies cognition, the mental processes underlying behavior. It uses information processing as a framework for understanding the mind. Perception, learning, problem solving, memory, attention, language and emotion are all well-researched areas as well. Cognitive psychology is associated with a school of thought known as cognitivism, whose adherents argue for an information processing model of mental function, informed by positivism and experimental psychology. Techniques and models from cognitive psychology are widely applied and form the mainstay of psychological theories in many areas of both research and applied psychology. Largely focusing on the development of the human mind through the life span, developmental psychology seeks to understand how people come to perceive, understand, and act within the world and how these processes change as they age. This may focus on intellectual, cognitive, neural, social, or moral development.
Some philosophers divide consciousness into phenomenal consciousness, which is experience itself, and access consciousness, which is the processing of the things in experience[47] Phenomenal consciousness is the state of being conscious, such as when we say "I am conscious." Access consciousness is being conscious of something in relation to abstract concepts, such as when one says "I am conscious of these words." Various forms of access consciousness include awareness, self-awareness, conscience, stream of consciousness, Husserl's phenomenology, and intentionality. The concept of phenomenal consciousness, in modern history, according to some, is closely related to the concept of qualia.
Social psychology links sociology with psychology in their shared study of the nature and causes of human social interaction, with an emphasis on how people think towards each other and how they relate to each other. The behavior and mental processes, both human and non-human, can be described through animal cognition, ethology, evolutionary psychology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with both their natural environment and the human social environment.
Motivation and emotion
Goya's Tio Paquete (1820).
For more details on this topic, see Motivation and Emotion.
Motivation is the driving force of desire behind all deliberate actions of human beings. Motivation is based on emotion — specifically, on the search for satisfaction (positive emotional experiences), and the avoidance of conflict; positive and negative are defined by the individual brain state, not by social norms: a person may be driven to self-injury or violence because their brain is conditioned to create a positive response to these actions. Motivation is important because it is involved in the performance of all learned responses.
Within psychology, conflict avoidance and the libido are seen to be primary motivators. Within economics motivation is often seen to be based on financial incentives, moral incentives, or coercive incentives. Religions generally posit divine or demonic influences.
Happiness, or being happy, is a human emotional condition. The definition of happiness is a common philosophical topic. Some people might define it as the best condition which a human can have — a condition of mental and physical health. Others may define it as freedom from want and distress; consciousness of the good order of things; assurance of one's place in the universe or society, inner peace, and so forth.
Human emotion has a significant influence on, or can even be said to control, human behavior, though historically many cultures and philosophers have for various reasons discouraged allowing this influence to go unchecked.
Emotional experiences perceived as pleasant, like love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction seen between refined emotions, which are socially learned, and survival oriented emotions, which are thought to be innate.
Human exploration of emotions as separate from other neurological phenomena is worthy of note, particularly in those cultures where emotion is considered separate from physiological state. In some cultural medical theories, to provide an example, emotion is considered so synonymous with certain forms of physical health that no difference is thought to exist. The Stoics believed excessive emotion was harmful, while some Sufi teachers (in particular, the poet and astronomer Omar Khayyám) felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy.
In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals, developed commonly in reaction to superior survival mechanisms and intelligent interaction with each other and the environment; as such, refined emotion is not in all cases as discrete and separate from natural neural function as was once assumed. Still, when humans function in civilized tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime.
Love and sexuality
A soldier and girl kissing on V-J Day, New York City.
For more details on this topic, see Love and Human sexuality.
Human sexuality, besides ensuring biological reproduction, has important social functions: it creates physical intimacy, bonds and hierarchies among individuals; may be directed to spiritual transcendence; and in a hedonistic sense to the enjoyment of activity involving sexual gratification. Sexual desire, or libido, is experienced as a bodily urge, often accompanied by strong emotions such as love, ecstasy and jealousy.
As with other human self-descriptions, humans propose that it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal, including a great many behaviors that are not directly connected with reproduction.
Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are sometimes determined by religious beliefs or social customs.
Many sexologists believe that the majority of Homo sapiens have the inherent capacity to be attracted to both males and females (a kind of universal potential bisexuality). In a variation of this, pioneering researcher Sigmund Freud believed that humans are born polymorphously perverse, which means that any number of objects could be a source of pleasure. According to Freud, humans then pass through five stages of psychosexual development (and can fixate on any stage because of various traumas during the process). For Alfred Kinsey, another influential sex researcher, people can fall anywhere along a continuous scale of sexual orientation (with only small minorities fully heterosexual or homosexual). Recent studies of neurology and genetics suggest people may be born with one sexual orientation or another, so there is not currently a clear consensus among sex researchers.[48][49]
Culture
For more details on this topic, see Culture.
Culture is defined here as a set of distinctive material, intellectual, emotional, and spiritual features of a social group, including art, literature, lifestyles, value systems, traditions, rituals, and beliefs. The link between human biology and human behavior and culture is often very close, making it difficult to clearly divide topics into one area or the other; as such, the placement of some subjects may be based primarily on convention.
Culture consists of values, social norms, and artifacts. A culture's values define what it holds to be important or ethical. Closely linked are norms, expectations of how people ought to behave, bound by tradition. Artifacts, or "material culture", are objects derived from the culture's values, norms, and understanding of the world.
The mainstream anthropological view of ‘culture’ implies that we most people experience a strong resistance when reminded that there is an animal as well as a spiritual aspect to human nature.[42]
Language
For more details on this topic, see Language.
The capacity humans have to transfer concepts, ideas and notions through speech and writing is unrivaled in known species. The faculty of speech is a defining feature of humanity, possibly predating phylogenetic separation of the modern population (see origin of language). Language is central to the communication between humans, as well as being central to the sense of identity that unites nations, cultures and ethnic groups.
The invention of writing systems around 5000 years ago allowed the preservation of language on material objects, and was a major step in cultural evolution. Language is closely tied to ritual and religion (cf. mantra, sacred text).
The science of linguistics describes the structure of language and the relationship between languages. There are approximately 6,000 different languages currently in use, including sign languages, and many thousands more that are considered extinct.
Art, music and literature
Allegory of Music (ca. 1594), a painting of a woman writing sheet music by Lorenzo Lippi.
For more details on this topic, see Art, Music, and Literature.
Artistic works have existed for almost as long as humankind, from early pre-historic art to contemporary art. Art is one of the most unusual aspects of human behavior and a key distinguishing feature of humans from other species.
As a form of cultural expression by humans, art may be defined by the pursuit of diversity and the usage of narratives of liberation and exploration (i.e. art history, art criticism, and art theory) to mediate its boundaries. This distinction may be applied to objects or performances, current or historical, and its prestige extends to those who made, found, exhibit, or own them.
In the modern use of the word, art is commonly understood to be the process or result of making material works which, from concept to creation, adhere to the "creative impulse" — that is, art is distinguished from other works by being in large part unprompted by necessity, by biological drive, or by any undisciplined pursuit of recreation.
Music is a natural intuitive phenomenon based on the three distinct and interrelated organization structures of rhythm, harmony, and melody. Listening to music is perhaps the most common and universal form of entertainment for humans, while learning and understanding it are popular disciplines. There are a wide variety of music genres and ethnic musics.
Literature, the body of written — and possibly oral — works, especially creative ones, includes prose, poetry and drama, both fiction and non-fiction. Literature includes such genres as epic, legend, myth, ballad, and folklore.
Sculpture of a man meditating.
Spirituality and religion
For more details on this topic, see Spirituality and Religion.
Spirituality, belief or involvement in matters of the soul or spirit, is one of the many different approaches humans take in trying to answer fundamental questions about humankind's place in the universe, the meaning of life, and the ideal way to live one's life. Though these topics have also been addressed by philosophy, and to some extent by science, spirituality is unique in that it focuses on mystical or supernatural concepts such as karma and God. However, critics would argue that spirituality does not actually answer any questions, and complicates the issues further by raising more questions.[50]
A more organized, but related, concept is religion — sometimes used interchangeably with "faith" — which is commonly defined as a belief system concerning the supernatural, sacred, or divine, and the moral codes, practices, values, institutions and rituals associated with such belief. In the course of its development, religion has taken on many forms that vary by culture and individual perspective.
Some of the chief questions and issues religions are concerned with include life after death (commonly involving belief in an afterlife), the origin of life (the source of a variety of origin beliefs), the nature of the universe (religious cosmology) and its ultimate fate (eschatology), and what is moral or immoral. A common source in religions for answers to these questions are transcendent divine beings such as deities or a singular God, although not all religions are theistic — many are nontheistic or ambiguous on the topic, particularly among the Eastern religions.
Although a majority of humans profess some variety of spiritual or religious belief, some are irreligious, lacking or rejecting belief in the supernatural or spiritual. Additionally, although most religions and spiritual beliefs are clearly distinct from science on both a philosophical and methodological level, the two are not generally considered to be mutually exclusive; a majority of humans hold a mix of both scientific and religious views. The distinction between philosophy and religion, on the other hand, is at times less clear, and the two are linked in such fields as the philosophy of religion and theology.
The Thinker, Artist's rendering of the sculpture by Auguste Rodin.
Philosophy and self-reflection
For more details on this topic, see Philosophy, Human self-reflection, and Human nature.
Philosophy is a discipline or field of study involving the investigation, analysis, and development of ideas at a general, abstract, or fundamental level. It is the discipline searching for a general understanding of values and reality by chiefly speculative means.
The core philosophical disciplines are logic, ontology or metaphysics, epistemology, and axiology, which includes the branches of ethics and aesthetics. Philosophy covers a very wide range of approaches, and is also used to refer to a worldview, to a perspective on an issue, or to the positions argued for by a particular philosopher or school of philosophy.
Plato and Aristotle in a detail from The School of Athens by Raphael.
Metaphysics is a branch of philosophy concerned with the study of first principles, being and existence (ontology). In between the doctrines of religion and science, stands the philosophical perspective of metaphysical cosmology. This ancient field of study seeks to draw logical conclusions about the nature of the universe, humanity, god, and/or their connections based on the extension of some set of presumed facts borrowed from religion and/or observation.
Humans often consider themselves to be the dominant species on Earth, and the most advanced in intelligence and ability to manage their environment. This belief is especially strong in modern Western culture. Alongside such claims of dominance is often found radical pessimism because of the frailty and brevity of human life.
Humanism is a philosophy which defines a socio-political doctrine the bounds of which are not constrained by those of locally developed cultures, but which seeks to include all of humanity and all issues common to human beings. Because spiritual beliefs of a community often manifests as religious doctrine, the history of which is as factious as it is unitive, secular humanism grew as an answer to the need for a common philosophy that transcended the cultural boundaries of local moral codes and religions. Many humanists are religious, however, and see humanism as simply a mature expression of a common truth present in most religions. Humanists affirm the possibility of an objective truth and accept that human perception of that truth is imperfect. The most basic tenets of humanism are that humans matter and can solve human problems, and that science, freedom of speech, rational thought, democracy, and freedom in the arts are worthy pursuits or goals for all peoples. Humanism depends chiefly on reason and logic without consideration for the supernatural.
In the mid- to late 20th century, humans achieved a level of technological mastery sufficient to leave the atmosphere of Earth for the first time, explore space and walk on the moon.
Science and technology
For more details on this topic, see Science and Technology.
Science is the discovery of knowledge about the world by verifiable means. Technology is the objects humans make to serve their purposes.
Human cultures are both characterized and differentiated by the objects that they make and use. Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery and jewelry that are particular to various regions and times.
Improvements in technology are passed from one culture to another. For instance, the cultivation of crops arose in several different locations, but quickly spread to be an almost ubiquitous feature of human life. Similarly, advances in weapons, architecture and metallurgy are quickly disseminated.
Such techniques can be passed on by oral tradition. The development of writing, itself a kind of technology, made it possible to pass information from generation to generation and from region to region with greater accuracy.
Together, these developments made possible the commencement of civilization and urbanization, with their inherently complex social arrangements. Eventually this led to the institutionalization of the development of new technology, and the associated understanding of the way the world functions. This science now forms a central part of human culture.
In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology, that is, the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scales and at the earliest times, begins by arguing for the big bang, a sort of cosmic expansion from which the universe itself is said to have erupted ~13.7 ± 0.2 billion (109) years ago. After its violent beginnings and until its very end, scientists then propose that the entire history of the universe has been an orderly progression governed by physical laws.
Race and ethnicity
For more details on this topic, see Race and Ethnic group.
Humans often categorize themselves in terms of race or ethnicity, although the validity of human races as true biological categories is questionable.[51] Human racial categories are based on both ancestry and visible traits, especially skin color and facial features. These categories may also carry some information on non-visible biological traits, such as the risk of developing particular diseases such as sickle-cell disease.[52]
Genetic studies have demonstrated that humans on the African continent are most genetically diverse (Y-chromosome and MtDNA lineages).[53] However, compared to many other animals, human gene sequences are remarkably homogeneous. It has been claimed that the majority of genetic variation occurs within "racial groups", with only 5 to 15% of total variation occurring between racial groups.[54] However, this remains an area of active debate.[55][56]
Ethnic groups, on the other hand, are more often linked by linguistic, cultural, ancestral, and national or regional ties. Self-identification with an ethnic group is based on kinship and descent. Race and ethnicity can lead to variant treatment and impact social identity, giving rise to racism and the theory of identity politics.
Society
For more details on this topic, see Society.
Society is the system of organizations and institutions arising from interaction between humans.
Government and politics
The United Nations complex in New York City, which houses one of the largest human political organizations in the world.
For more details on this topic, see Government, Politics, and State.
A state is an organized political community occupying a definite territory, having an organized government, and possessing internal and external sovereignty. Recognition of the state's claim to independence by other states, enabling it to enter into international agreements, is often important to the establishment of its statehood. The "state" can also be defined in terms of domestic conditions, specifically, as conceptualized by Max Weber, "a state is a human community that (successfully) claims the monopoly of the 'legitimate' use of physical force within a given territory."[57]
Government can be defined as the political means of creating and enforcing laws; typically via a bureaucratic hierarchy.
Politics is the process by which decisions are made within groups. Although the term is generally applied to behavior within governments, politics is also observed in all human group interactions, including corporate, academic, and religious institutions. Many different political systems exist, as do many different ways of understanding them, and many definitions overlap. The most common form of government worldwide is a republic, however other examples include monarchy, social democracy, military dictatorship and theocracy.
All of these issues have a direct relationship with economics.
The atomic bombings of Hiroshima and Nagasaki immediately killed over 120,000 humans.
War
For more details on this topic, see War.
War is a state of widespread conflict between states, organizations, or relatively large groups of people, which is characterized by the use of lethal violence between combatants or upon civilians. It is estimated that during the 20th century between 167 and 188 million humans died as a result of war.[58]
A common perception of war is a series of military campaigns between at least two opposing sides involving a dispute over sovereignty, territory, resources, religion or other issues. A war said to liberate an occupied country is sometimes characterized as a "war of liberation", while a war between internal elements of a state is a civil war.
There have been a wide variety of rapidly advancing tactics throughout the history of war, ranging from conventional war to asymmetric warfare to total war and unconventional warfare. Techniques include hand to hand combat, the use of ranged weapons, propaganda and ethnic cleansing. Military intelligence has often played a key role in determining victory and defeat. In modern warfare, soldiers and armoured fighting vehicles are used to control the land, warships the sea, and air power the sky. Outer space has recently become a factor in warfare as well, although no actual warfare is currently carried out in space. War is a strong catalyst in politics, history and technology. Important inventions such as medicine, navigation, metallurgy, mass production, nuclear power and computers having been completely or partially driven by war.[citation needed]
Throughout history there has been a constant struggle between defense and offense, armour, and the weapons designed to breach it. Modern examples include the bunker buster bomb, and the bunkers which they are designed to destroy.
Trade and economics
Buyers and sellers bargain in Chichicastenango Market, Guatemala.
For more details on this topic, see Trade and Economics.
Trade is the voluntary exchange of goods, services, or both, and a form of economics. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade.
Trade exists for many reasons. Because of specialization and division of labor, most people concentrate on a small aspect of manufacturing or service, trading their labour for products. Trade exists between regions because different regions have an absolute or comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade between locations benefits both locations.
Economics is a social science that studies the production, distribution, trade and consumption of goods and services.
Economics, which focuses on measurable variables, is broadly divided into two main branches: microeconomics, which deals with individual agents, such as households and businesses, and macroeconomics, which considers the economy as a whole, in which case it considers aggregate supply and demand for money, capital and commodities. Aspects receiving particular attention in economics are resource allocation, production, distribution, trade, and competition. Economic logic is increasingly applied to any problem that involves choice under scarcity or determining economic value. Mainstream economics focuses on how prices reflect supply and demand, and uses equations to predict consequences of decisions.
Effect on ecosystems
For more details on this topic, see Environmentalism.
This short section requires expansion.
The neutrality of this article is disputed.Please see the discussion on the talk page.
Humanity is often criticized for destructively affecting the natural environment. This destruction has been described as the 7th mass extinction of the history of earth, possibly one of the fastest ever (the 6th wiped out the dinosaurs). Some, such as E. O. Wilson of Harvard University, predict that man's destruction of the biosphere could cause the extinction of one-half of all species in the next 100 years.
One study asserts that after the Chernobyl disaster the benefit to the environment due to man leaving the region outweighed the negative effects of the heavy radiation.[59]Environmentalist James Lovelock even stated:
“
I have wondered if the small volumes of nuclear waste from power production should be stored in tropical forests and other habitats in need of a reliable guardian against their destruction by greedy developers
”
Humankind's impact on the environment has slowly become a major issue for human society, as people become more conscious of their effects on the environment. The documentation of humankind's negative effects on the environment in books such as Silent Spring or documentaries such as An Inconvenient Truth draw attention to environmental crises, and various steps are taken to remedy them. Regardless, humankind's effect on its environment continues to be a controversial issue.
From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is about modern humans. For other human species, see Homo (genus). For other uses, see Human (disambiguation).
HumanFossil range: Pleistocene - Recent
Image of a man and a woman on the Pioneer plaque.
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Primates
Family:
Hominidae
Genus:
Homo
Species:
H. sapiens
Subspecies:
H. s. sapiens
Trinomial name
Homo sapiens sapiensLinnaeus, 1758
Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: "wise man" or "knowing man") in the family Hominidae (the great apes).[1][2] Humans have a highly developed brain capable of abstract reasoning, language, and introspection. This mental capability, combined with an erect body carriage that frees their upper limbs for manipulating objects, has allowed humans to make far greater use of tools than any other species. Humans originated in Africa about 200,000 years ago, but they now inhabit every continent, with a total population of over 6.6 billion as of 2007[3].
Like most primates, humans are social by nature; however, humans are particularly adept at utilizing systems of communication for self-expression, the exchange of ideas, and organization. Humans create complex social structures composed of cooperating and competing groups, ranging in scale from small families and partnerships to species-wide political, scientific and economic unions. Social interactions between humans have also established an extremely wide variety of traditions, rituals, ethics, values, social norms, and laws which form the basis of human society. Humans also have a marked appreciation for beauty and aesthetics which, combined with the human desire for self-expression, has led to cultural innovations such as art, literature and music.
Humans are also noted for their desire to understand and influence the world around them, seeking to explain and manipulate natural phenomena through science, philosophy, mythology and religion. This natural curiosity has led to the development of advanced tools and skills; humans are the only known species to build fires, cook their food, clothe themselves, and use numerous other technologies.
Contents[show]
1 History
1.1 Evolution
1.2 Rise of civilization
1.3 Habitat and population
2 Biology
2.1 Physiology and genetics
2.2 Life cycle
2.3 Diet
3 Psychology
3.1 Consciousness and thought
3.2 Motivation and emotion
3.3 Love and sexuality
4 Culture
4.1 Language
4.2 Art, music and literature
4.3 Spirituality and religion
4.4 Philosophy and self-reflection
4.5 Science and technology
4.6 Race and ethnicity
5 Society
5.1 Government and politics
5.2 War
5.3 Trade and economics
6 Effect on ecosystems
7 See also
8 References
9 External links
//
History
Evolution
For more details on this topic, see Human evolution.
Reconstructed skull of Peking Man, a representative of the extinct species believed to be the nearest ancestor of Homo sapiens, Homo erectus.
The scientific study of human evolution encompasses the development of the genus Homo, but usually involves studying other hominids and hominines as well, such as Australopithecus. "Modern humans" are defined as the Homo sapiens species, of which the only extant subspecies is Homo sapiens sapiens; Homo sapiens idaltu (roughly translated as "elder wise man"), the other known subspecies, is extinct.[4] Anatomically modern humans appear in the fossil record in Africa about 130,000 years ago.[5][6]
The closest living relatives of Homo sapiens are the two species of chimpanzee: the Bonobo (Pan paniscus) and the Common Chimpanzee (Pan troglodytes). These species are equally close (they share the same common ancestor), the main difference between them is the social organization: matriarchal for the Bonobo and patriarchal for the Common Chimpanzee. Full genome sequencing resulted in the conclusion that "after 6.5 million years of separate evolution, the differences between bonobo/chimpanzee and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice". In fact, 98.4% of the DNA sequence is identical between the two Pan species and human.[7][8][9][10] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from gorillas about eight million years ago. However, a hominid skull discovered in Chad in 2001, classified as Sahelanthropus tchadensis, is approximately seven million years old, which may indicate an earlier divergence.[11]
There are two prominent scientific theories of the origins of contemporary humans. They concern the relationship between modern humans and other hominids. The single-origin, or "out-of-Africa", hypothesis proposes that modern humans evolved in Africa and later migrated outwards to replace hominids in other parts of the world. The multiregional hypothesis, on the other hand, proposes that modern humans evolved, at least in part, from independent hominid populations.[12]
Geneticists Lynn Jorde and Henry Harpending of the University of Utah proposed that the variation in human DNA is minute compared to that of other species, and that during the Late Pleistocene, the human population was reduced to a small number of breeding pairs — no more than 10,000 and possibly as few as 1,000 — resulting in a very small residual gene pool. Various reasons for this hypothetical bottleneck have been postulated, the most popular[citation needed] being the Toba catastrophe theory.
Human evolution is characterized by a number of important physiological trends, including the expansion of the brain cavity and brain itself, which is typically 1,400 cm³ in volume, over twice that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning and language acquisition in juvenile humans. Physical anthropologists argue that a reorganization of the structure of the brain is more important than cranial expansion itself. Other significant evolutionary changes included a reduction of the canine tooth, development of bipedal locomotion, and the descent of the larynx and hyoid bone, making speech possible. How these trends are related and what their role is in the evolution of complex social organization and culture are matters of ongoing debate.[13][14]
Rise of civilization
The rise of agriculture led to the foundation of stable human settlements.
For more details on this topic, see History of the world.
The most widely accepted view among current anthropologists is that Homo sapiens originated in the African savanna around 200,000 BP (Before Present), descending from Homo erectus, had colonized Eurasia and Oceania by 40,000 BP, and finally colonized the Americas approximately 10,000 years ago.[15] They displaced Homo neanderthalensis and other species descended from Homo erectus (which had colonized Eurasia as early as 2 million years ago) through more successful reproduction and competition for resources.
The earliest humans were hunter-gatherers, a lifestyle well-suited to the savanna. They generally lived in small, nomadic groups. Around 10,000 years ago, the advent of agriculture prompted the Neolithic Revolution. Access to a stable food source led to the formation of permanent human settlements, the domestication of animals, and the use of metal tools. Agriculture also encouraged trade and cooperation, leading to complex societies. Villages developed into thriving civilizations in regions such as the Middle East's Fertile Crescent.
Around 6,000 years ago, the first proto-states developed in Mesopotamia, Egypt and the Indus Valley. Military forces were formed for protection, and government bureaucracies for administration. States cooperated and competed for resources, in some cases waging wars. Around 2,000 – 3,000 years ago, some states, such as Persia, China, and Rome, developed through conquest into the first expansive empires. Influential religions, such as the Abrahamic and Dharmic religions, also rose to prominence at this time.
The late Middle Ages saw the rise of revolutionary ideas and technologies. In China, an advanced and urbanized economy promoted innovations such as printing and the compass, while the Islamic Golden Age saw major scientific advancements in Muslim empires. In Europe, the rediscovery of classical learning and inventions such as the printing press led to the Renaissance in the 14th century. Over the next 500 years, exploration and imperialistic conquest brought much of the Americas, Asia, and Africa under European control, leading to later struggles for independence. The Scientific Revolution in the 17th century and the Industrial Revolution in the 18th – 19th centuries promoted major innovations in transport, such as the railway and automobile; energy development, such as coal and electricity; and government, such as representative democracy and Communism.
As a result of such changes, modern humans live in a world that has become increasingly globalized and interconnected. Although this has encouraged the growth of science, art, and technology, it has also led to culture clashes, the development and use of weapons of mass destruction, and increased environmental destruction and pollution.
Habitat and population
For more details on this topic, see Demography and World population.
Early human settlements were dependent on proximity to water and, depending on the lifestyle, other natural resources, such as fertile land for growing crops and grazing livestock, or seasonally by hunting populations of prey. However, humans have a great capacity for altering their habitats by various methods, such as through irrigation, urban planning, construction, transport, and manufacturing goods, and with the advent of large-scale trade and transport infrastructure, proximity to these resources has become unnecessary, and in many places these factors are no longer a driving force behind the growth and decline of a population. Nonetheless, the manner in which a habitat is altered is often a major determinant in population change.
Technology has allowed humans to colonize all of the continents and adapt to all climates. Within the last few decades, humans have explored Antarctica, the ocean depths, and space, although long-term habitation of these environments is not yet possible. With a population of over six billion, humans are among the most numerous of the large mammals. Most humans (61%) live in Asia. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 0.5% in Oceania. (See list of countries by population and list of countries by population density.)
Human habitation within closed ecological systems in hostile environments, such as Antarctica and outer space, is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with no more than thirteen humans in space at any given time. Between 1969 and 1972, two humans at a time spent brief intervals on the Moon. As of 2007, no other celestial body has been visited by human beings, although there has been a continuous human presence in outer space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000.
From AD 1800 to 2000, the human population increased from one billion to six billion. In 2004, around 2.5 billion out of 6.3 billion people (39.7%) lived in urban areas, and this percentage is expected to rise throughout the 21st century. Problems for humans living in cities include various forms of pollution and crime,[16] especially in inner city and suburban slums. Benefits of urban living include increased literacy, access to the global canon of human knowledge and decreased susceptibility to rural famines.
Humans have had a dramatic effect on the environment. It has been hypothesized that in the past, human predation has contributed to the extinction of a number of species; as humans are not generally preyed on themselves, humans have been described as the ultimate superpredators.[17] Currently, through land development and pollution, humans are thought to be the main contributor to global climate change.[18] This is believed to be a major contributor to the ongoing Holocene extinction event, a mass extinction which, if it continues at its current rate, is predicted to wipe out half of all species over the next century.[19][20]
Biology
For more details on this topic, see Human biology.
Physiology and genetics
For more details on this topic, see Human anatomy, Human physical appearance, and Human genetics.
An old diagram of a male human skeleton.
Human body types vary substantially. Although body size is largely determined by genes, it is also significantly influenced by environmental factors such as diet and exercise. The average height of an adult human is about 5 to 6 feet (1.5 to 1.8 m) tall, although this varies significantly from place to place.[21][22] Humans are capable of fully bipedal locomotion, thus leaving their arms available for manipulating objects using their hands, aided especially by opposable thumbs. As human physiology has not fully adapted to bipedalism, the pelvic region and vertebral column tend to become worn, causing the elderly to have difficulty in walking.[citation needed]
Although humans appear relatively hairless compared to other primates, with notable hair growth occurring chiefly on the top of the head, underarms and pubic area, the average human has more hair follicles on his or her body than the average chimpanzee. The main distinction is that human hairs are shorter, finer, and less heavily pigmented than the average chimpanzee's, thus making them harder to see.[23]
An Inuit woman, circa 1907.
The hue of human hair and skin is determined by the presence of pigments called melanins. Human skin hues can range from very dark brown to very pale pink, while human hair ranges from blond to brown to red to, most commonly, black.[24] Most researchers believe that skin darkening was an adaptation that evolved as a protection against ultraviolet solar radiation, as melanin is an effective sun-block.[25] The skin pigmentation of contemporary humans is geographically stratified, and in general correlates with the level of ultraviolet radiation. Human skin also has a capacity to darken (sun tanning) in response to exposure to ultraviolet radiation.[26][27]
The average sleep requirement is between seven and eight hours a day for an adult and nine to ten hours for a child; elderly people usually sleep for six to seven hours. Experiencing less sleep than this is common in modern societies; this sleep deprivation can lead to negative effects. A sustained restriction of adult sleep to four hours per day has been shown to correlate with changes in physiology and mental state, including fatigue, aggression, and bodily discomfort.
Humans are an eukaryotic species. Each diploid cell has two sets of 23 chromosomes, each set received from one parent. There are 22 pairs of autosomes and one pair of sex chromosomes. By present estimates, humans have approximately 20,000 – 25,000 genes. Like other mammals, humans have an XY sex-determination system, so that females have the sex chromosomes XX and males have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes, such as hemophilia, affect men more often than women.
Human embryo at 5 weeks.
Life cycle
The human life cycle is similar to that of other placental mammals. New humans develop viviparously from conception. An egg is usually fertilized inside the female by sperm from the male through sexual intercourse, though the recent technology of in vitro fertilization is occasionally used. The fertilized egg, called a zygote, divides inside the female's uterus to become an embryo, which over a period of thirty-eight weeks (9 months) of gestation becomes a human fetus. After this span of time, the fully-grown fetus is expelled from the female's body and breathes independently as an infant for the first time. At this point, most modern cultures recognize the baby as a person entitled to the full protection of the law, though some jurisdictions extend personhood to human fetuses while they remain in the uterus.
Two young human girls.
Compared with that of other species, human childbirth is dangerous. Painful labors lasting twenty-four hours or more are not uncommon, and may result in injury, or even death, to the child or mother. This is because of both the relatively large fetal head circumference (for housing the brain) and the mother's relatively narrow pelvis (a trait required for successful bipedalism, by way of natural selection).[28][29] The chances of a successful labor increased significantly during the 20th century in wealthier countries with the advent of new medical technologies. In contrast, pregnancy and natural childbirth remain relatively hazardous ordeals in developing regions of the world, with maternal death rates approximately 100 times more common than in developed countries.[30]
In developed countries, infants are typically 3 – 4 kg (6 – 9 pounds) in weight and 50 – 60 cm (20 – 24 inches) in height at birth.[31] However, low birth weight is common in developing countries, and contributes to the high levels of infant mortality in these regions.[32] Helpless at birth, humans continue to grow for some years, typically reaching sexual maturity at 12 to 15 years of age. Human girls continue to grow physically until around the age of 18, and human boys until around age 21. The human life span can be split into a number of stages: infancy, childhood, adolescence, young adulthood, adulthood and old age. The lengths of these stages, however — particularly the later ones — are not fixed.
There are striking differences in life expectancy around the world. The developed world is quickly getting older, with the median age around 40 years (highest in Monaco at 45.1 years), while in the developing world, the median age is 15 – 20 years (lowest in Uganda at 14.8 years). Life expectancy at birth in Hong Kong, China is 84.8 years for a female and 78.9 for a male, while in Swaziland, primarily because of AIDS, it is 31.3 years for both sexes.[33] While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older.[34]
The number of centenarians (humans of age 100 years or older) in the world was estimated by the United Nations at 210,000 in 2002.[35] At least one person, Jeanne Calment, is known to have reached the age of 122 years; higher ages have been claimed but they are not well substantiated. Worldwide, there are 81 men aged 60 or older for every 100 women of that age group, and among the oldest, there are 53 men for every 100 women.
The philosophical questions of when human personhood begins and whether it persists after death are the subject of considerable debate. The prospect of death causes unease or fear for most humans. Burial ceremonies are characteristic of human societies, often inspired by beliefs in an afterlife or immortality.
Diet
Early Homo sapiens employed a "hunter-gatherer" method as their primary means of food collection, involving combining stationary plant and fungal food sources (such as fruits, grains, tubers, and mushrooms) with wild game which must be hunted and killed in order to be consumed. It is believed that humans have used fire to prepare and cook food prior to eating since the time of their divergence from Homo erectus.
Humans are omnivorous, capable of consuming both plant and animal products. The view of humans as omnivores is supported by the evidence that both a pure animal and a pure vegetable diet can lead to deficiency diseases in humans[citation needed]. A pure animal diet can, for instance, lead to scurvy, while a pure vegetarian diet can lead to deficiency of a number of nutrients, including Vitamin B12. Supplementation, particularly for vitamin B12, is highly recommended for people living on a pure vegetable diet[36]. Some humans have chosen to abstain from eating some or all meat for religious, ethical, ecological, or health reasons.
The human diet is prominently reflected in human culture, and has led to the development of food science. In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. Lack of food remains a serious problem, with about 300,000 people starving to death every year.[37] Childhood malnutrition is also common and contributes to the global burden of disease.[38] However global food distribution is not even, and obesity among some human populations has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed, and a few developing countries. The United States Center for Disease Control states that 32% of American adults over the age of 20 are obese, while 66.5% are obese or overweight. Obesity is caused by consuming more calories than are expended, with many attributing excessive weight gain to a combination of overeating and insufficient exercise.
At least ten thousand years ago, humans developed agriculture,[39] which has substantially altered the kind of food people eat. This has led to increased populations, the development of cities, and because of increased population density, the wider spread of infectious diseases. The types of food consumed, and the way in which they are prepared, has varied widely by time, location, and culture.
Psychology
A sketch of the human brain, imposed upon the profile of Michelangelo's David - sketch by artist Priyan Weerappuli.
For more details on this topic, see Human brain and Mind.
The human brain is the center of the central nervous system in humans, as well as the primary control center for the peripheral nervous system. The brain controls "lower", or involuntary, autonomic activities such as the respiration, and digestion. The brain also controls "higher" order, conscious activities, such as thought, reasoning, and abstraction.[40] These cognitive processes constitute the mind, and, along with their behavioral consequences, are studied in the field of psychology.
The human brain is generally regarded as more capable of these higher order activities, and more "intelligent" in general, than that of any other species.[citation needed] While other animals are capable of creating structures and using simple tools — mostly as a result of instinct and learning through mimicry — human technology is vastly more complex, constantly evolving and improving with time.[citation needed] Even the most ancient human tools and structures are far more advanced than any structure or tool created by any other animal.[41]
Modern Anthropology has tended to bear out Darwin's proposition that "the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind".[42]
Consciousness and thought
For more details on this topic, see Consciousness and Cognition.
The human ability to think abstractly may be unparalleled in the animal kingdom. Humans are one of only six species to pass the mirror test — which tests whether an animal recognizes its reflection as an image of itself — along with chimpanzees, orangutans, dolphins, and possibly pigeons. In October 2006, three elephants at the Bronx Zoo also passed this test.[43] Humans under the age of 2 typically fail this test.[44] However, this may be a matter of degree rather than a sharp divide. Monkeys have been trained to apply abstract rules in tasks.[45]
The brain perceives the external world through the senses, and each individual human is influenced greatly by his or her experiences, leading to subjective views of existence and the passage of time.
Humans are variously said to possess consciousness, self-awareness, and a mind, which correspond roughly to the mental processes of thought. These are said to possess qualities such as self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. The extent to which the mind constructs or experiences the outer world is a matter of debate, as are the definitions and validity of many of the terms used above. The philosopher of cognitive science Daniel Dennett, for example, argues that there is no such thing as a narrative centre called the "mind", but that instead there is simply a collection of sensory inputs and outputs: different kinds of "software" running in parallel.[46]
Humans study the more physical aspects of the mind and brain, and by extension of the nervous system, in the field of neurology, the more behavioral in the field of psychology, and a sometimes loosely-defined area between in the field of psychiatry, which treats mental illness and behavioral disorders. Psychology does not necessarily refer to the brain or nervous system, and can be framed purely in terms of phenomenological or information processing theories of the mind. Increasingly, however, an understanding of brain functions is being included in psychological theory and practice, particularly in areas such as artificial intelligence, neuropsychology, and cognitive neuroscience.
The nature of thought is central to psychology and related fields. Cognitive psychology studies cognition, the mental processes underlying behavior. It uses information processing as a framework for understanding the mind. Perception, learning, problem solving, memory, attention, language and emotion are all well-researched areas as well. Cognitive psychology is associated with a school of thought known as cognitivism, whose adherents argue for an information processing model of mental function, informed by positivism and experimental psychology. Techniques and models from cognitive psychology are widely applied and form the mainstay of psychological theories in many areas of both research and applied psychology. Largely focusing on the development of the human mind through the life span, developmental psychology seeks to understand how people come to perceive, understand, and act within the world and how these processes change as they age. This may focus on intellectual, cognitive, neural, social, or moral development.
Some philosophers divide consciousness into phenomenal consciousness, which is experience itself, and access consciousness, which is the processing of the things in experience[47] Phenomenal consciousness is the state of being conscious, such as when we say "I am conscious." Access consciousness is being conscious of something in relation to abstract concepts, such as when one says "I am conscious of these words." Various forms of access consciousness include awareness, self-awareness, conscience, stream of consciousness, Husserl's phenomenology, and intentionality. The concept of phenomenal consciousness, in modern history, according to some, is closely related to the concept of qualia.
Social psychology links sociology with psychology in their shared study of the nature and causes of human social interaction, with an emphasis on how people think towards each other and how they relate to each other. The behavior and mental processes, both human and non-human, can be described through animal cognition, ethology, evolutionary psychology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with both their natural environment and the human social environment.
Motivation and emotion
Goya's Tio Paquete (1820).
For more details on this topic, see Motivation and Emotion.
Motivation is the driving force of desire behind all deliberate actions of human beings. Motivation is based on emotion — specifically, on the search for satisfaction (positive emotional experiences), and the avoidance of conflict; positive and negative are defined by the individual brain state, not by social norms: a person may be driven to self-injury or violence because their brain is conditioned to create a positive response to these actions. Motivation is important because it is involved in the performance of all learned responses.
Within psychology, conflict avoidance and the libido are seen to be primary motivators. Within economics motivation is often seen to be based on financial incentives, moral incentives, or coercive incentives. Religions generally posit divine or demonic influences.
Happiness, or being happy, is a human emotional condition. The definition of happiness is a common philosophical topic. Some people might define it as the best condition which a human can have — a condition of mental and physical health. Others may define it as freedom from want and distress; consciousness of the good order of things; assurance of one's place in the universe or society, inner peace, and so forth.
Human emotion has a significant influence on, or can even be said to control, human behavior, though historically many cultures and philosophers have for various reasons discouraged allowing this influence to go unchecked.
Emotional experiences perceived as pleasant, like love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction seen between refined emotions, which are socially learned, and survival oriented emotions, which are thought to be innate.
Human exploration of emotions as separate from other neurological phenomena is worthy of note, particularly in those cultures where emotion is considered separate from physiological state. In some cultural medical theories, to provide an example, emotion is considered so synonymous with certain forms of physical health that no difference is thought to exist. The Stoics believed excessive emotion was harmful, while some Sufi teachers (in particular, the poet and astronomer Omar Khayyám) felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy.
In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals, developed commonly in reaction to superior survival mechanisms and intelligent interaction with each other and the environment; as such, refined emotion is not in all cases as discrete and separate from natural neural function as was once assumed. Still, when humans function in civilized tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime.
Love and sexuality
A soldier and girl kissing on V-J Day, New York City.
For more details on this topic, see Love and Human sexuality.
Human sexuality, besides ensuring biological reproduction, has important social functions: it creates physical intimacy, bonds and hierarchies among individuals; may be directed to spiritual transcendence; and in a hedonistic sense to the enjoyment of activity involving sexual gratification. Sexual desire, or libido, is experienced as a bodily urge, often accompanied by strong emotions such as love, ecstasy and jealousy.
As with other human self-descriptions, humans propose that it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal, including a great many behaviors that are not directly connected with reproduction.
Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are sometimes determined by religious beliefs or social customs.
Many sexologists believe that the majority of Homo sapiens have the inherent capacity to be attracted to both males and females (a kind of universal potential bisexuality). In a variation of this, pioneering researcher Sigmund Freud believed that humans are born polymorphously perverse, which means that any number of objects could be a source of pleasure. According to Freud, humans then pass through five stages of psychosexual development (and can fixate on any stage because of various traumas during the process). For Alfred Kinsey, another influential sex researcher, people can fall anywhere along a continuous scale of sexual orientation (with only small minorities fully heterosexual or homosexual). Recent studies of neurology and genetics suggest people may be born with one sexual orientation or another, so there is not currently a clear consensus among sex researchers.[48][49]
Culture
For more details on this topic, see Culture.
Culture is defined here as a set of distinctive material, intellectual, emotional, and spiritual features of a social group, including art, literature, lifestyles, value systems, traditions, rituals, and beliefs. The link between human biology and human behavior and culture is often very close, making it difficult to clearly divide topics into one area or the other; as such, the placement of some subjects may be based primarily on convention.
Culture consists of values, social norms, and artifacts. A culture's values define what it holds to be important or ethical. Closely linked are norms, expectations of how people ought to behave, bound by tradition. Artifacts, or "material culture", are objects derived from the culture's values, norms, and understanding of the world.
The mainstream anthropological view of ‘culture’ implies that we most people experience a strong resistance when reminded that there is an animal as well as a spiritual aspect to human nature.[42]
Language
For more details on this topic, see Language.
The capacity humans have to transfer concepts, ideas and notions through speech and writing is unrivaled in known species. The faculty of speech is a defining feature of humanity, possibly predating phylogenetic separation of the modern population (see origin of language). Language is central to the communication between humans, as well as being central to the sense of identity that unites nations, cultures and ethnic groups.
The invention of writing systems around 5000 years ago allowed the preservation of language on material objects, and was a major step in cultural evolution. Language is closely tied to ritual and religion (cf. mantra, sacred text).
The science of linguistics describes the structure of language and the relationship between languages. There are approximately 6,000 different languages currently in use, including sign languages, and many thousands more that are considered extinct.
Art, music and literature
Allegory of Music (ca. 1594), a painting of a woman writing sheet music by Lorenzo Lippi.
For more details on this topic, see Art, Music, and Literature.
Artistic works have existed for almost as long as humankind, from early pre-historic art to contemporary art. Art is one of the most unusual aspects of human behavior and a key distinguishing feature of humans from other species.
As a form of cultural expression by humans, art may be defined by the pursuit of diversity and the usage of narratives of liberation and exploration (i.e. art history, art criticism, and art theory) to mediate its boundaries. This distinction may be applied to objects or performances, current or historical, and its prestige extends to those who made, found, exhibit, or own them.
In the modern use of the word, art is commonly understood to be the process or result of making material works which, from concept to creation, adhere to the "creative impulse" — that is, art is distinguished from other works by being in large part unprompted by necessity, by biological drive, or by any undisciplined pursuit of recreation.
Music is a natural intuitive phenomenon based on the three distinct and interrelated organization structures of rhythm, harmony, and melody. Listening to music is perhaps the most common and universal form of entertainment for humans, while learning and understanding it are popular disciplines. There are a wide variety of music genres and ethnic musics.
Literature, the body of written — and possibly oral — works, especially creative ones, includes prose, poetry and drama, both fiction and non-fiction. Literature includes such genres as epic, legend, myth, ballad, and folklore.
Sculpture of a man meditating.
Spirituality and religion
For more details on this topic, see Spirituality and Religion.
Spirituality, belief or involvement in matters of the soul or spirit, is one of the many different approaches humans take in trying to answer fundamental questions about humankind's place in the universe, the meaning of life, and the ideal way to live one's life. Though these topics have also been addressed by philosophy, and to some extent by science, spirituality is unique in that it focuses on mystical or supernatural concepts such as karma and God. However, critics would argue that spirituality does not actually answer any questions, and complicates the issues further by raising more questions.[50]
A more organized, but related, concept is religion — sometimes used interchangeably with "faith" — which is commonly defined as a belief system concerning the supernatural, sacred, or divine, and the moral codes, practices, values, institutions and rituals associated with such belief. In the course of its development, religion has taken on many forms that vary by culture and individual perspective.
Some of the chief questions and issues religions are concerned with include life after death (commonly involving belief in an afterlife), the origin of life (the source of a variety of origin beliefs), the nature of the universe (religious cosmology) and its ultimate fate (eschatology), and what is moral or immoral. A common source in religions for answers to these questions are transcendent divine beings such as deities or a singular God, although not all religions are theistic — many are nontheistic or ambiguous on the topic, particularly among the Eastern religions.
Although a majority of humans profess some variety of spiritual or religious belief, some are irreligious, lacking or rejecting belief in the supernatural or spiritual. Additionally, although most religions and spiritual beliefs are clearly distinct from science on both a philosophical and methodological level, the two are not generally considered to be mutually exclusive; a majority of humans hold a mix of both scientific and religious views. The distinction between philosophy and religion, on the other hand, is at times less clear, and the two are linked in such fields as the philosophy of religion and theology.
The Thinker, Artist's rendering of the sculpture by Auguste Rodin.
Philosophy and self-reflection
For more details on this topic, see Philosophy, Human self-reflection, and Human nature.
Philosophy is a discipline or field of study involving the investigation, analysis, and development of ideas at a general, abstract, or fundamental level. It is the discipline searching for a general understanding of values and reality by chiefly speculative means.
The core philosophical disciplines are logic, ontology or metaphysics, epistemology, and axiology, which includes the branches of ethics and aesthetics. Philosophy covers a very wide range of approaches, and is also used to refer to a worldview, to a perspective on an issue, or to the positions argued for by a particular philosopher or school of philosophy.
Plato and Aristotle in a detail from The School of Athens by Raphael.
Metaphysics is a branch of philosophy concerned with the study of first principles, being and existence (ontology). In between the doctrines of religion and science, stands the philosophical perspective of metaphysical cosmology. This ancient field of study seeks to draw logical conclusions about the nature of the universe, humanity, god, and/or their connections based on the extension of some set of presumed facts borrowed from religion and/or observation.
Humans often consider themselves to be the dominant species on Earth, and the most advanced in intelligence and ability to manage their environment. This belief is especially strong in modern Western culture. Alongside such claims of dominance is often found radical pessimism because of the frailty and brevity of human life.
Humanism is a philosophy which defines a socio-political doctrine the bounds of which are not constrained by those of locally developed cultures, but which seeks to include all of humanity and all issues common to human beings. Because spiritual beliefs of a community often manifests as religious doctrine, the history of which is as factious as it is unitive, secular humanism grew as an answer to the need for a common philosophy that transcended the cultural boundaries of local moral codes and religions. Many humanists are religious, however, and see humanism as simply a mature expression of a common truth present in most religions. Humanists affirm the possibility of an objective truth and accept that human perception of that truth is imperfect. The most basic tenets of humanism are that humans matter and can solve human problems, and that science, freedom of speech, rational thought, democracy, and freedom in the arts are worthy pursuits or goals for all peoples. Humanism depends chiefly on reason and logic without consideration for the supernatural.
In the mid- to late 20th century, humans achieved a level of technological mastery sufficient to leave the atmosphere of Earth for the first time, explore space and walk on the moon.
Science and technology
For more details on this topic, see Science and Technology.
Science is the discovery of knowledge about the world by verifiable means. Technology is the objects humans make to serve their purposes.
Human cultures are both characterized and differentiated by the objects that they make and use. Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery and jewelry that are particular to various regions and times.
Improvements in technology are passed from one culture to another. For instance, the cultivation of crops arose in several different locations, but quickly spread to be an almost ubiquitous feature of human life. Similarly, advances in weapons, architecture and metallurgy are quickly disseminated.
Such techniques can be passed on by oral tradition. The development of writing, itself a kind of technology, made it possible to pass information from generation to generation and from region to region with greater accuracy.
Together, these developments made possible the commencement of civilization and urbanization, with their inherently complex social arrangements. Eventually this led to the institutionalization of the development of new technology, and the associated understanding of the way the world functions. This science now forms a central part of human culture.
In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology, that is, the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scales and at the earliest times, begins by arguing for the big bang, a sort of cosmic expansion from which the universe itself is said to have erupted ~13.7 ± 0.2 billion (109) years ago. After its violent beginnings and until its very end, scientists then propose that the entire history of the universe has been an orderly progression governed by physical laws.
Race and ethnicity
For more details on this topic, see Race and Ethnic group.
Humans often categorize themselves in terms of race or ethnicity, although the validity of human races as true biological categories is questionable.[51] Human racial categories are based on both ancestry and visible traits, especially skin color and facial features. These categories may also carry some information on non-visible biological traits, such as the risk of developing particular diseases such as sickle-cell disease.[52]
Genetic studies have demonstrated that humans on the African continent are most genetically diverse (Y-chromosome and MtDNA lineages).[53] However, compared to many other animals, human gene sequences are remarkably homogeneous. It has been claimed that the majority of genetic variation occurs within "racial groups", with only 5 to 15% of total variation occurring between racial groups.[54] However, this remains an area of active debate.[55][56]
Ethnic groups, on the other hand, are more often linked by linguistic, cultural, ancestral, and national or regional ties. Self-identification with an ethnic group is based on kinship and descent. Race and ethnicity can lead to variant treatment and impact social identity, giving rise to racism and the theory of identity politics.
Society
For more details on this topic, see Society.
Society is the system of organizations and institutions arising from interaction between humans.
Government and politics
The United Nations complex in New York City, which houses one of the largest human political organizations in the world.
For more details on this topic, see Government, Politics, and State.
A state is an organized political community occupying a definite territory, having an organized government, and possessing internal and external sovereignty. Recognition of the state's claim to independence by other states, enabling it to enter into international agreements, is often important to the establishment of its statehood. The "state" can also be defined in terms of domestic conditions, specifically, as conceptualized by Max Weber, "a state is a human community that (successfully) claims the monopoly of the 'legitimate' use of physical force within a given territory."[57]
Government can be defined as the political means of creating and enforcing laws; typically via a bureaucratic hierarchy.
Politics is the process by which decisions are made within groups. Although the term is generally applied to behavior within governments, politics is also observed in all human group interactions, including corporate, academic, and religious institutions. Many different political systems exist, as do many different ways of understanding them, and many definitions overlap. The most common form of government worldwide is a republic, however other examples include monarchy, social democracy, military dictatorship and theocracy.
All of these issues have a direct relationship with economics.
The atomic bombings of Hiroshima and Nagasaki immediately killed over 120,000 humans.
War
For more details on this topic, see War.
War is a state of widespread conflict between states, organizations, or relatively large groups of people, which is characterized by the use of lethal violence between combatants or upon civilians. It is estimated that during the 20th century between 167 and 188 million humans died as a result of war.[58]
A common perception of war is a series of military campaigns between at least two opposing sides involving a dispute over sovereignty, territory, resources, religion or other issues. A war said to liberate an occupied country is sometimes characterized as a "war of liberation", while a war between internal elements of a state is a civil war.
There have been a wide variety of rapidly advancing tactics throughout the history of war, ranging from conventional war to asymmetric warfare to total war and unconventional warfare. Techniques include hand to hand combat, the use of ranged weapons, propaganda and ethnic cleansing. Military intelligence has often played a key role in determining victory and defeat. In modern warfare, soldiers and armoured fighting vehicles are used to control the land, warships the sea, and air power the sky. Outer space has recently become a factor in warfare as well, although no actual warfare is currently carried out in space. War is a strong catalyst in politics, history and technology. Important inventions such as medicine, navigation, metallurgy, mass production, nuclear power and computers having been completely or partially driven by war.[citation needed]
Throughout history there has been a constant struggle between defense and offense, armour, and the weapons designed to breach it. Modern examples include the bunker buster bomb, and the bunkers which they are designed to destroy.
Trade and economics
Buyers and sellers bargain in Chichicastenango Market, Guatemala.
For more details on this topic, see Trade and Economics.
Trade is the voluntary exchange of goods, services, or both, and a form of economics. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade.
Trade exists for many reasons. Because of specialization and division of labor, most people concentrate on a small aspect of manufacturing or service, trading their labour for products. Trade exists between regions because different regions have an absolute or comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade between locations benefits both locations.
Economics is a social science that studies the production, distribution, trade and consumption of goods and services.
Economics, which focuses on measurable variables, is broadly divided into two main branches: microeconomics, which deals with individual agents, such as households and businesses, and macroeconomics, which considers the economy as a whole, in which case it considers aggregate supply and demand for money, capital and commodities. Aspects receiving particular attention in economics are resource allocation, production, distribution, trade, and competition. Economic logic is increasingly applied to any problem that involves choice under scarcity or determining economic value. Mainstream economics focuses on how prices reflect supply and demand, and uses equations to predict consequences of decisions.
Effect on ecosystems
For more details on this topic, see Environmentalism.
This short section requires expansion.
The neutrality of this article is disputed.Please see the discussion on the talk page.
Humanity is often criticized for destructively affecting the natural environment. This destruction has been described as the 7th mass extinction of the history of earth, possibly one of the fastest ever (the 6th wiped out the dinosaurs). Some, such as E. O. Wilson of Harvard University, predict that man's destruction of the biosphere could cause the extinction of one-half of all species in the next 100 years.
One study asserts that after the Chernobyl disaster the benefit to the environment due to man leaving the region outweighed the negative effects of the heavy radiation.[59]Environmentalist James Lovelock even stated:
“
I have wondered if the small volumes of nuclear waste from power production should be stored in tropical forests and other habitats in need of a reliable guardian against their destruction by greedy developers
”
Humankind's impact on the environment has slowly become a major issue for human society, as people become more conscious of their effects on the environment. The documentation of humankind's negative effects on the environment in books such as Silent Spring or documentaries such as An Inconvenient Truth draw attention to environmental crises, and various steps are taken to remedy them. Regardless, humankind's effect on its environment continues to be a controversial issue.
Subscribe to:
Posts (Atom)