Difference between revisions of "Human Being"

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(New page: Image:lighterstill.jpg == History == === Origin === The scientific study of human evolution encompasses the development of the genus ''Homo'', but usually involv...)
 
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== History ==
 
== History ==
 
=== Origin ===
 
=== Origin ===
  
The scientific study of [[human evolution]] encompasses the development of the genus ''[[Homo (genus)|Homo]]'', but usually involves studying other [[hominidae|hominids]] and [[homininae|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 human"), the other known subspecies, is extinct.<ref>[http://www.anth.ucsb.edu/projects/human/# Human evolution: the fossil evidence in 3D], by Philip L. Walker and Edward H. Hagen, Dept of Anthropology, University of California, Santa Barbara, retrieved [[April 5]], [[2005]].</ref> Anatomically modern humans appear in the fossil record in Africa about 130,000 years ago.<ref>[http://www.mnh.si.edu/anthro/humanorigins/ha/sap.htm Human Ancestors Hall: ''Homo Sapiens''] - URL retrieved [[October 13]], [[2006]]</ref><ref>{{cite journal |author=Alemseged Z, Coppens Y, Geraads D |title=Hominid cranium from Omo: Description and taxonomy of Omo-323-1976-896 |journal=Am J Phys Anthropol |volume=117 |issue=2 |pages=103-12 |year=2002 |id=PMID 11815945}}</ref>
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The scientific study of [[human]] [[evolution]] encompasses the development of the genus ''[[Homo (genus)|Homo]]'', but usually involves studying other [[hominidae|hominids]] and [[homininae|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 human"), the other known subspecies, is extinct. [http://www.anth.ucsb.edu/projects/human/#] Anatomically modern humans appear in the fossil record in Africa about 130,000 years ago.[http://www.mnh.si.edu/anthro/humanorigins/ha/sap.htm]  
  
The closest living relatives of ''Homo sapiens'' are two distinct species of the genus Pan: the [[Bonobo]] (''Pan paniscus'') and the [[Common Chimpanzee]] (''Pan troglodytes''). These species 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]]&nbsp;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, 95 per cent of the DNA sequence is identical between the two ''Pan'' species and human.<ref>[[Frans de Waal]], ''Bonobo''. Berkeley: University of California Press, 1997. ISBN 0-520-20535-9 [http://www.2think.org/bonobo.shtml]</ref><ref>{{cite journal | author=Britten RJ | title=Divergence between samples of chimpanzee and human DNA sequences is 5%, counting indels | url=http://www.pnas.org/cgi/content/full/99/21/13633 | journal=Proc Natl Acad Sci U S A | year=2002 | pages=13633-5 | volume=99 | issue=21 | id=PMID 12368483}}</ref><ref>{{cite journal | author = Wildman D, Uddin M, Liu G, Grossman L, Goodman M | title = Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: enlarging genus Homo. | url=http://www.pnas.org/cgi/content/full/100/12/7181 | journal = Proc Natl Acad Sci U S A | volume = 100 | issue = 12 | pages = 7181-8 | year = 2003 | id = PMID 12766228}}</ref><ref>{{cite journal | author = Ruvolo M | title = Molecular phylogeny of the hominoids: inferences from multiple independent DNA sequence data sets. | url=http://mbe.oxfordjournals.org/cgi/reprint/14/3/248 | journal = Mol Biol Evol | volume = 14 | issue = 3 | pages = 248-65 | year = 1997 | id = PMID 9066793}}</ref> It has been estimated that the human [[lineage (evolution)|lineage]] diverged from that of chimpanzees about five million&nbsp;years ago, and from [[gorilla]]s about  eight million&nbsp;years ago. However, a hominid skull discovered in [[Chad]] in 2001, classified as ''[[Sahelanthropus tchadensis]]'', is approximately seven million&nbsp;years old, which may indicate an earlier divergence.<ref>{{cite journal | author = Brunet M, Guy F, Pilbeam D, Mackaye H, Likius A, Ahounta D, Beauvilain A, Blondel C, Bocherens H, Boisserie J, De Bonis L, Coppens Y, Dejax J, Denys C, Duringer P, Eisenmann V, Fanone G, Fronty P, Geraads D, Lehmann T, Lihoreau F, Louchart A, Mahamat A, Merceron G, Mouchelin G, Otero O, Pelaez Campomanes P, Ponce De Leon M, Rage J, Sapanet M, Schuster M, Sudre J, Tassy P, Valentin X, Vignaud P, Viriot L, Zazzo A, Zollikofer C | title = A new hominid from the Upper Miocene of  Chad, Central Africa.  | url=http://www.nature.com/nature/journal/v418/n6894/full/nature00879.html | journal = Nature | volume = 418 | issue = 6894 | pages = 145-51 | year = 2002 | id = PMID 12110880}}</ref>
 
  
The [[Recent African Origin]] (RAO), or "out-of-Africa", hypothesis proposes that modern humans evolved in Africa and later [[human migration|migrated]] outwards to replace hominids in other parts of the world. Evidence from [[Archaeogenetics]] accumulating since the 1990s has lent strong support to RAO and has marginalized the  competing [[multiregional hypothesis]],  which proposed that modern humans evolved, at least in part, from independent hominid populations.<ref>Eswaran, Vinayak, Harpending, Henry & Rogers, Alan R. ''[http://www.sciencedirect.com/science/article/B6WJS-4G3SC6X-1/2/aae7c2810f0d87628e228363c0e1bd66 Genomics refutes an exclusively African origin of humans]'', Journal of Human Evolution, In Press, Corrected Proof, retrieved [[May 6]], [[2005]].</ref>
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<center>see the documentary film: [http://www.becominghuman.org/ '''''Becoming Human''''']</center>
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The closest living relatives of ''Homo sapiens'' are two distinct species of the genus Pan: the [[Bonobo]] (''Pan paniscus'') and the [[Common Chimpanzee]] (''Pan troglodytes''). These species 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]]&nbsp;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, 95 per cent of the DNA sequence is identical between the two ''Pan'' species and human.[[Frans de Waal]], ''Bonobo'' ISBN 0-520-20535-9 [http://www.2think.org/bonobo.shtml] [http://www.pnas.org/cgi/content/full/99/21/13633] [http://www.pnas.org/cgi/content/full/100/12/7181][http://mbe.oxfordjournals.org/cgi/reprint/14/3/248]| It has been estimated that the human [[lineage (evolution)|lineage]] diverged from that of chimpanzees about five million&nbsp;years ago, and from [[gorilla]]s about  eight million&nbsp;years ago. However, a hominid skull discovered in [[Chad]] in 2001, classified as ''[[Sahelanthropus tchadensis]]'', is approximately seven million&nbsp;years old, which may indicate an earlier divergence. [http://www.nature.com/nature/journal/v418/n6894/full/nature00879.html]
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The [[Recent African Origin]] (RAO), or "out-of-Africa", hypothesis proposes that modern humans evolved in Africa and later [[human migration|migrated]] outwards to replace hominids in other parts of the world. Evidence from [[Archaeogenetics]] accumulating since the 1990s has lent strong support to RAO and has marginalized the  competing [[multiregional hypothesis]],  which proposed that modern humans evolved, at least in part, from independent hominid populations. [http://www.sciencedirect.com/science/article/B6WJS-4G3SC6X-1/2/aae7c2810f0d87628e228363c0e1bd66]  
  
 
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. They also propose 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, one of those is the [[Toba catastrophe theory]].
 
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. They also propose 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, one of those is the [[Toba catastrophe theory]].
  
Human evolution is characterized by a number of important morphological, developmental, physiological and behavioral changes which have taken place since the split between the last common ancestor of ''Homo'' and ''Pan''. The primary change, both in terms of chronology and in terms of it being the trait that defines the human [[subtribe]] the [[Hominina]], was the evolution of a bipedal locomotor adaptation from an arboreal or semi-arboreal locomotor adaptation, with all its attendant adaptations, such as a valgus knee, low intermembral index (long legs relative to the arms) and reduced upper body strength.{{Fact|date=November 2007}} Following this was the evolution of a larger [[Cranial capacity|brain cavity]] and brain itself, which is typically 1,400&nbsp;cm³ in modern humans; over twice that of a chimpanzee or gorilla. Other significant morphological changes included: the evolution of a power and precision grip;{{Fact|date=November 2007}} a reduced masticatory system; a reduction of the [[canine tooth]]; and the descent of the [[larynx]] and [[hyoid bone]], making speech possible. With respect to development, 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 anthropology|Physical anthropologists]] argue that a reorganization of the structure of the brain is more important than cranial expansion itself.  One important physiological change in humans was the evolution of hidden estrus or [[concealed ovulation]] in females, which may have coincided with the evolution of important behavioral changes, such as [[pair bond]]ing. Another significant behavioral change includes the development of [[material culture]], or the (over time) increasingly wide variety of human-made objects which are used to manipulate humans' physical and social environments. How all these changes are related and what their role is in the evolution of complex social organization and culture are matters of ongoing debate.<ref>Boyd, Robert & Silk, Joan B. (2003). ''How Humans Evolved''. New York: Norton & Company. ISBN 0-393-97854-0.</ref><ref>Dobzhansky, Theodosius (1963). ''Anthropology and the natural sciences-The problem of human evolution'', ''Current Anthropology '4'' (2): 138-148.</ref>
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Human evolution is characterized by a number of important morphological, developmental, physiological and behavioral changes which have taken place since the split between the last common ancestor of ''Homo'' and ''Pan''. The primary change, both in terms of chronology and in terms of it being the trait that defines the human [[subtribe]] the [[Hominina]], was the evolution of a bipedal locomotor adaptation from an arboreal or semi-arboreal locomotor adaptation, with all its attendant adaptations, such as a valgus knee, low intermembral index (long legs relative to the arms) and reduced upper body strength. Following this was the evolution of a larger [[Cranial capacity|brain cavity]] and brain itself, which is typically 1,400&nbsp;cm³ in modern humans; over twice that of a chimpanzee or gorilla. Other significant morphological changes included: the evolution of a power and precision grip;
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a reduced masticatory system; a reduction of the [[canine tooth]]; and the descent of the [[larynx]] and [[hyoid bone]], making speech possible. With respect to development, 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 anthropology|Physical anthropologists]] argue that a reorganization of the structure of the brain is more important than cranial expansion itself.  One important physiological change in humans was the evolution of hidden estrus or [[concealed ovulation]] in females, which may have coincided with the evolution of important behavioral changes, such as [[pair bond]]ing. Another significant behavioral change includes the development of [[material culture]], or the (over time) increasingly wide variety of human-made objects which are used to manipulate humans' physical and social environments. How all these changes are related and what their role is in the evolution of complex social organization and culture are matters of ongoing debate.(''How Humans Evolved'', ISBN 0-393-97854-0]
  
 
=== Rise of civilization ===
 
=== Rise of civilization ===
  
[[Image:Farmer plowing.jpg|thumb|250px|The rise of [[agriculture]] led to the foundation of stable human settlements.]]
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The most widely accepted view among current [[anthropology|anthropologists]] is that ''Homo sapiens'' originated in the African [[savanna]] around 200,000 BP ([[Before Present]]), descending from ''[[Homo erectus]]'', had inhabited [[Eurasia]] and [[Oceania]] by 40,000 BP, and finally inhabited the [[Americas]] approximately 10,000&nbsp;years ago. [http://cogweb.ucla.edu/ep/Templeton_02.html "Out of Africa again and again"] They displaced ''[[Homo neanderthalensis]]'' and other species descended from ''Homo erectus'' (which had inhabited Eurasia as early as 2 million&nbsp;years ago) through more successful reproduction and competition for resources.
{{details more|History of the world}}
 
 
 
The most widely accepted view among current [[anthropology|anthropologists]] is that ''Homo sapiens'' originated in the African [[savanna]] around 200,000 BP ([[Before Present]]), descending from ''[[Homo erectus]]'', had inhabited [[Eurasia]] and [[Oceania]] by 40,000 BP, and finally inhabited the [[Americas]] approximately 10,000&nbsp;years ago.<ref>Templeton, Alan (2002). [http://cogweb.ucla.edu/ep/Templeton_02.html "Out of Africa again and again"] ''Nature'' 416: 45 - 51.</ref> They displaced ''[[Homo neanderthalensis]]'' and other species descended from ''Homo erectus'' (which had inhabited Eurasia as early as 2 million&nbsp;years ago) through more successful reproduction and competition for resources.
 
  
 
Up until only around 10,000 years ago, all humans lived as [[hunter-gatherer]]s (with some communities persisting until this day). They generally lived in small, [[nomad]]ic groups. The advent of [[agriculture]] prompted the [[Neolithic Revolution]]. Access to food surplus led to the formation of permanent human settlements, the [[domestication]] of animals, and the use of [[metalworking|metal tools]]. Agriculture also encouraged [[trade]] and cooperation, leading to complex societies. [[Village]]s developed into thriving [[civilization]]s in regions such as the [[Middle East]]'s [[Fertile Crescent]].
 
Up until only around 10,000 years ago, all humans lived as [[hunter-gatherer]]s (with some communities persisting until this day). They generally lived in small, [[nomad]]ic groups. The advent of [[agriculture]] prompted the [[Neolithic Revolution]]. Access to food surplus led to the formation of permanent human settlements, the [[domestication]] of animals, and the use of [[metalworking|metal tools]]. Agriculture also encouraged [[trade]] and cooperation, leading to complex societies. [[Village]]s developed into thriving [[civilization]]s in regions such as the [[Middle East]]'s [[Fertile Crescent]].
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== Habitat and population ==
 
== Habitat and population ==
{{details more|Demography|World population}}
 
[[Image:Fromvictoriapeakatnight.jpg|thumb|right|275px|Humans have structured their environment in extensive ways in order to adapt to problems such as high population density, as shown in this image of an Asian [[city]], [[Hong Kong]].]]
 
  
 
Early human settlements were dependent on proximity to [[water resources|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 [[habitat (ecology)|habitats]] by various methods, such as through [[irrigation]], [[urban planning]], [[construction]], [[transport]], and [[manufacturing]] goods. 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.
 
Early human settlements were dependent on proximity to [[water resources|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 [[habitat (ecology)|habitats]] by various methods, such as through [[irrigation]], [[urban planning]], [[construction]], [[transport]], and [[manufacturing]] goods. 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.
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Human habitation within [[closed ecological system]]s 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 [[exploration of the Moon|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]]; however, humans have made [[robot]]s that have visited other celestial bodies.
 
Human habitation within [[closed ecological system]]s 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 [[exploration of the Moon|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]]; however, humans have made [[robot]]s that have visited other celestial bodies.
  
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 area]]s, and this percentage is expected to rise throughout the 21st century. Problems for humans living in [[city|cities]] include various forms of [[pollution]] and [[crime]],<ref>[http://www.ojp.usdoj.gov/bjs/abstract/usrv98.htm Urban, Suburban, and Rural Victimization, 1993-98] U.S. Department of Justice, Bureau of Justice Statistics,. Accessed 29 Oct 2006</ref> 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]].
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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 area]]s, and this percentage is expected to rise throughout the 21st century. Problems for humans living in [[city|cities]] include various forms of [[pollution]] and [[crime]],[http://www.ojp.usdoj.gov/bjs/abstract/usrv98.htm] 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 [[natural environment|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 [[apex predator|superpredators]].<ref>''[[Scientific American]]'' (1998). [http://www.csulb.edu/~kmacd/346IQ.html Evolution and General Intelligence: Three hypotheses on the evolution of general intelligence].</ref> Currently, through land development and [[pollution]], humans are thought to be the main contributor to global [[climate change]].<ref>{{cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/007.htm|title=www.grida.no/climate/ipcc_tar/wg1/007.htm<!-- INSERT TITLE -->|accessdate=2007-05-30}}</ref> This is believed to be a major contributor to the ongoing [[Holocene extinction event]], a [[extinction event|mass extinction]] which, if it continues at its current rate, is predicted to wipe out half of all species over the next century.<ref>[[American Association for the Advancement of Science]]. [http://atlas.aaas.org/index.php?sub=foreword Foreword]. ''AAAS Atlas of Population & Environment''.</ref><ref>[[E. O. Wilson|Wilson, E.O.]] (2002). ''in The Future of Life''.</ref>
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Humans have had a dramatic effect on the [[natural environment|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 [[apex predator|superpredators]].'[[Scientific American]]'' [http://www.csulb.edu/~kmacd/346IQ.html Evolution and General Intelligence: Three hypotheses on the evolution of general intelligence]. Currently, through land development and [[pollution]], humans are thought to be the main contributor to global [[climate change]]. [http://www.grida.no/climate/ipcc_tar/wg1/007.htm] This is believed to be a major contributor to the ongoing [[Holocene extinction event]], a [[extinction event|mass extinction]] which, if it continues at its current rate, is predicted to wipe out half of all species over the next century.<ref>[[American Association for the Advancement of Science]]. [http://atlas.aaas.org/index.php?sub=foreword Foreword]. ''AAAS Atlas of Population & Environment''. [[E. O. Wilson|Wilson, E.O.]] (2002). ''in The Future of Life''.</ref>
  
 
== Biology ==
 
== Biology ==
{{details more|Human biology}}
 
 
 
=== Physiology and genetics ===
 
=== Physiology and genetics ===
{{details more|Human anatomy|Human physical appearance|Human genetics}}
 
[[Image:Skeleton diagram.svg|thumbnail|200px|left|An old diagram of a male [[human skeleton]].]]
 
Human body types vary substantially. Although body size is largely determined by [[gene]]s, it is also significantly influenced by environmental factors such as [[diet (nutrition)|diet]] and [[exercise]]. The average [[human height|height]] of an adult human is about 5 to 6&nbsp;[[foot (length)|feet]] (1.5 to 1.8 m) tall, although this varies significantly from place to place.<ref>{{cite journal | author = de Beer H | title = Observations on the history of Dutch physical stature from the late-Middle Ages to the present. | journal = Econ Hum Biol | volume = 2 | issue = 1 | pages = 45-55 | year = 2004 | id = PMID 15463992}}</ref><ref>"Pygmy." Britannica Concise Encyclopedia. Encyclopædia Britannica, Inc., 2006. Answers.com Accessed 30 Oct. 2006. http://www.answers.com/topic/pygmy</ref> Humans are capable of fully bipedal [[terrestrial locomotion in animals|locomotion]], thus leaving their arms available for manipulating objects using their [[hand]]s, aided especially by opposable [[thumb]]s.
 
  
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.<ref>[http://www.freerepublic.com/focus/f-news/966532/posts ''Why Humans and Their Fur Parted Way''] by Nicholas Wade, ''New York Times'', [[August 19]] [[2003]], retrieved [[March 17]], [[2006]].</ref>
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Human body types vary substantially. Although body size is largely determined by [[gene]]s, it is also significantly influenced by environmental factors such as [[diet (nutrition)|diet]] and [[exercise]]. The average [[human height|height]] of an adult human is about 5 to 6&nbsp;[[foot (length)|feet]] (1.5 to 1.8 m) tall, although this varies significantly from place to place. Britannica Concise Encyclopedia. Encyclopædia Britannica, Inc., 2006. [http://www.answers.com/topic/pygmy] Humans are capable of fully bipedal [[terrestrial locomotion in animals|locomotion]], thus leaving their arms available for manipulating objects using their [[hand]]s, aided especially by opposable [[thumb]]s.  
  
[[Image:Inuit women 1907.jpg|thumb|right|An [[Inuit]] woman, circa 1907.]]
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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.<ref>[http://www.freerepublic.com/focus/f-news/966532/posts ''Why Humans and Their Fur Parted Way'' by Nicholas Wade, ''New York Times'',
 
 
The hue of human hair and skin is determined by the presence of [[pigment]]s called [[melanin]]s. Human skin hues can range from very dark brown to very pale pink, while human hair ranges from [[blond]] to [[brown hair|brown]] to [[red hair|red]] to, most commonly, [[black hair|black]].<ref>{{cite journal | author=Rogers, Alan R., Iltis, David & Wooding, Stephen | year=2004 | title=Genetic variation at the MC1R locus and the time since loss of human body hair | journal=Current Anthropology | volume=45 | issue=1 | pages=105-108}}</ref>, depending on the amount of melanin (an effective sun blocking pigment) in the skin. Most researchers believe that skin darkening was an adaptation that evolved as a protection against [[ultraviolet]] [[solar radiation]]. More recently, however, it has been argued that particular skin colors are an adaptation to balance folate, which is destroyed by ultraviolet radiation, and vitamin D, which requires sunlight to form.<ref>Jablonski, N.G. & Chaplin, G. (2000). ''[http://www.bgsu.edu/departments/chem/faculty/leontis/chem447/PDF_files/Jablonski_skin_color_2000.pdf The evolution of human skin coloration]'' (pdf), 'Journal of Human Evolution 39: 57-106.</ref> 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.<ref>Harding, Rosalind M., Eugene Healy, Amanda J. Ray, Nichola S. Ellis, Niamh Flanagan, Carol Todd, Craig Dixon, Antti Sajantila, Ian J. Jackson, Mark A. Birch-Machin, and Jonathan L. Rees (2000). ''Evidence for variable selective pressures at MC1R''. American Journal of Human Genetics 66: 1351 – 1361.</ref><ref>Robin, Ashley (1991). ''Biological Perspectives on Human Pigmentation''. Cambridge: Cambridge University Press.</ref>
 
  
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The hue of human hair and skin is determined by the presence of [[pigment]]s called [[melanin]]s. Human skin hues can range from very dark brown to very pale pink, while human hair ranges from [[blond]] to [[brown hair|brown]] to [[red hair|red]] to, most commonly, [[black hair|black]]., depending on the amount of melanin (an effective sun blocking pigment) in the skin. Most researchers believe that skin darkening was an adaptation that evolved as a protection against [[ultraviolet]] [[solar radiation]]. More recently, however, it has been argued that particular skin colors are an adaptation to balance folate, which is destroyed by ultraviolet radiation, and vitamin D, which requires sunlight to form.[http://www.bgsu.edu/departments/chem/faculty/leontis/chem447/PDF_files/Jablonski_skin_color_2000.pdf]The evolution of human skin coloration]'' (pdf), 'Journal of Human Evolution 39: 57-106. 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.
 
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.
 
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 [[eukaryote|eukaryotic]] species. Each [[ploidy|diploid]] [[cell (biology)|cell]] has two sets of 23 [[chromosome]]s, each set received from one parent. There are 22 pairs of [[autosome]]s and one pair of [[sex-determination system|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 [[female]]s have the sex chromosomes XX and [[male]]s have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that [[recessive gene|recessive]] diseases associated with X-linked genes, such as [[hemophilia]], affect men more often than women.
 
Humans are an [[eukaryote|eukaryotic]] species. Each [[ploidy|diploid]] [[cell (biology)|cell]] has two sets of 23 [[chromosome]]s, each set received from one parent. There are 22 pairs of [[autosome]]s and one pair of [[sex-determination system|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 [[female]]s have the sex chromosomes XX and [[male]]s have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that [[recessive gene|recessive]] diseases associated with X-linked genes, such as [[hemophilia]], affect men more often than women.
 
[[Image:Tubal Pregnancy with embryo.jpg|thumb|left|Human [[embryo]] at 5 weeks.]]
 
  
 
=== Life cycle ===
 
=== Life cycle ===
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The human [[biological life cycle|life cycle]] is similar to that of other [[placenta]]l mammals. New humans develop [[vivipary|viviparously]] from [[fertilization|conception]]. An [[ovum|egg]] is usually fertilized inside the female by [[spermatozoon|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.
 
The human [[biological life cycle|life cycle]] is similar to that of other [[placenta]]l mammals. New humans develop [[vivipary|viviparously]] from [[fertilization|conception]]. An [[ovum|egg]] is usually fertilized inside the female by [[spermatozoon|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.
  
[[Image:Two young girls at Camp Christmas Seals.jpg|thumb|right|250px|Two young human [[girl]]s.]]
+
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 and/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). 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..  
 
 
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 and/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).<ref>{{cite journal | author = LaVelle M | title = Natural selection and developmental sexual variation in the human pelvis | journal = Am J Phys Anthropol | volume = 98 | issue = 1 | pages = 59-72 | year = 1995 | id = PMID 8579191}}</ref><ref>{{cite journal | author = Correia H, Balseiro S, De Areia M | title = Sexual dimorphism in the human pelvis: testing a new hypothesis | journal = Homo | volume = 56 | issue = 2 | pages = 153-60 | year = 2005 | id = PMID 16130838}}</ref> 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.<ref>{{cite journal | author = Rush D | title = Nutrition and maternal mortality in the developing world. | journal = Am J Clin Nutr | volume = 72 | issue = 1 Suppl | pages = 212 S-240 S | year = 2000 | id = PMID 10871588}}</ref>
 
  
In developed countries, infants are typically 3 – 4 kg (6 – 9&nbsp;pounds) in weight and 50 – 60 cm (20 – 24&nbsp;inches) in height at birth.<ref>{{cite web|url=http://childinfo.org/areas/birthweight/|title=Low Birthweight|accessdate=2007-05-30}}</ref> However, low [[birth weight]] is common in developing countries, and contributes to the high levels of [[infant mortality]] in these regions.<ref>{{cite journal | author = Khor G | title = Update on the prevalence of malnutrition among children in Asia. | journal = Nepal Med Coll J | volume = 5 | issue = 2 | pages = 113-22 | year = 2003 | id = PMID 15024783}}</ref> Helpless at birth, humans continue to grow for some years, typically reaching [[sexual maturity]] at 12 to 15&nbsp;years of age. Human [[girl]]s continue to grow physically until around the age of 18, and human [[boy]]s until around age 21. The human life span can be split into a number of stages: infancy, [[childhood]], [[adolescence]], [[young adulthood]], [[adult]]hood and [[old age]]. The lengths of these stages, however — particularly the later ones — are not fixed.
+
In developed countries, infants are typically 3 – 4 kg (6 – 9&nbsp;pounds) in weight and 50 – 60 cm (20 – 24&nbsp;inches) in height at birth.[http://childinfo.org/areas/birthweight/|title=Low Birthweight] However, low [[birth weight]] is common in developing countries, and contributes to the high levels of [[infant mortality]] in these regions. Helpless at birth, humans continue to grow for some years, typically reaching [[sexual maturity]] at 12 to 15&nbsp;years of age. Human [[girl]]s continue to grow physically until around the age of 18, and human [[boy]]s until around age 21. The human life span can be split into a number of stages: infancy, [[childhood]], [[adolescence]], [[young adulthood]], [[adult]]hood 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&nbsp;years (highest in [[Monaco]] at 45.1&nbsp;years), while in the [[third world|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.<ref>[http://hdr.undp.org/hdr2006/ "Human Development Report 2006,"] [[United Nations Development Programme]], pp. 363-366, [[November 9]] [[2006]]</ref> While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older.<ref>[[https://www.cia.gov/library/publications/the-world-factbook/ ''The World Factbook'']], U.S. Central Intelligence Agency, retrieved [[April 2]], [[2005]].</ref>
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There are striking differences in [[life expectancy]] around the world. The developed world is quickly getting older, with the median age around 40&nbsp;years (highest in [[Monaco]] at 45.1&nbsp;years), while in the [[third world|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.<ref>[http://hdr.undp.org/hdr2006/ "Human Development Report 2006,"] [[United Nations Development Programme]], pp. 363-366, [[November 9]] [[2006]]</ref> While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older. [[https://www.cia.gov/library/publications/the-world-factbook/ ''The World Factbook'']]
  
 
The number of [[centenarian]]s (humans of age 100 years or older) in the world was estimated by the [[United Nations]] at 210,000 in 2002.<ref>[http://www.un.org/ageing/note5713.doc.htm U.N. Statistics on Population Ageing], United Nations press release, February 28, 2002, retrieved April 2, 2005</ref> 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 number of [[centenarian]]s (humans of age 100 years or older) in the world was estimated by the [[United Nations]] at 210,000 in 2002.<ref>[http://www.un.org/ageing/note5713.doc.htm U.N. Statistics on Population Ageing], United Nations press release, February 28, 2002, retrieved April 2, 2005</ref> 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.
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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 [[cooking|cook]] food prior to eating since the time of their divergence from ''[[Homo erectus]]''.  
 
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 [[cooking|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. A pure animal diet can, for instance, lead to [[scurvy]], while a pure plant 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 plant diet.<ref>{{cite web |url=http://www.vegansociety.com/html/food/nutrition/ |title=Healthy choices on a vegan diet |accessdate=2007-02-14 |publisher=[[Vegan Society]]}}</ref> However, according to [[American Dietetic Association]] and the [[Dietitians of Canada]], properly planned [[vegetarian]] and [[vegan]] diets are nutritionally adequate and healthy.<ref>{{cite web|url=http://www.eatright.org/cps/rde/xchg/ada/hs.xsl/advocacy_933_ENU_HTML.htm |title=American Dietetic Association}}</ref>
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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. A pure animal diet can, for instance, lead to [[scurvy]], while a pure plant 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 plant diet.[http://www.vegansociety.com/html/food/nutrition/] However, according to [[American Dietetic Association]] and the [[Dietitians of Canada]], properly planned [[vegetarian]] and [[vegan]] diets are nutritionally adequate and healthy.[http://www.eatright.org/cps/rde/xchg/ada/hs.xsl/advocacy_933_ENU_HTML.htm]
  
 
The human diet is prominently reflected in human culture, and has led to the development of [[food science]].
 
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.<ref>[http://www.who.int/healthinfo/bod/en/index.html Death and DALY estimates for 2002 by cause for WHO Member States] World Health Organisation. Accessed 29 Oct 2006</ref> Childhood malnutrition is also common and contributes to the global burden of disease.<ref>{{cite journal | author = Murray C, Lopez A | title = Global mortality, disability, and the contribution of risk factors: Global Burden of Disease Study. | journal = Lancet | volume = 349 | issue = 9063 | pages = 1436-42 | year = 1997 | id = PMID 9164317}}</ref> 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 country|developed]], and a few [[developing countries]]. The United States [[Centers for Disease Control]] (CDC) state 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 [[calorie]]s than are expended, with many attributing excessive weight gain to a combination of overeating and insufficient [[exercise]].
+
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.<ref>[http://www.who.int/healthinfo/bod/en/index.html Death and DALY estimates for 2002 by cause for WHO Member States] World Health Organisation. Accessed 29 Oct 2006</ref> Childhood malnutrition is also common and contributes to the global burden of disease. 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 country|developed]], and a few [[developing countries]]. The United States [[Centers for Disease Control]] (CDC) state 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 [[calorie]]s than are expended, with many attributing excessive weight gain to a combination of overeating and insufficient [[exercise]].
  
 
At least ten thousand years ago, [[History of agriculture|humans developed agriculture]],<ref>[http://www.archaeology.org/9707/newsbriefs/squash.html Earliest agriculture in the Americas]
 
At least ten thousand years ago, [[History of agriculture|humans developed agriculture]],<ref>[http://www.archaeology.org/9707/newsbriefs/squash.html Earliest agriculture in the Americas]
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== Psychology ==
 
== Psychology ==
 
[[Image:Davidbrain.JPG|thumb|right|A sketch of the human brain, imposed upon the profile of [[Michelangelo]]'s [[David (Michelangelo)|David]] - sketch by artist Priyan Weerappuli.]]
 
{{details more|Human brain|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 nervous system|autonomic]] activities such as the [[respiration (physiology)|respiration]], and [[digestion]]. The brain also controls "higher" order, conscious activities, such as [[thought]], [[reason]]ing, and [[abstraction]].<ref>[http://www.pbs.org/wnet/brain/3d/index.html 3-D Brain Anatomy], ''The Secret Life of the Brain'', Public Broadcasting Service, retrieved [[April 3]] [[2005]].</ref> These [[mental function|cognitive processes]] constitute the [[mind]], and, along with their [[behavior]]al consequences, are studied in the field of [[psychology]].
 
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 nervous system|autonomic]] activities such as the [[respiration (physiology)|respiration]], and [[digestion]]. The brain also controls "higher" order, conscious activities, such as [[thought]], [[reason]]ing, and [[abstraction]].<ref>[http://www.pbs.org/wnet/brain/3d/index.html 3-D Brain Anatomy], ''The Secret Life of the Brain'', Public Broadcasting Service, retrieved [[April 3]] [[2005]].</ref> These [[mental function|cognitive processes]] constitute the [[mind]], and, along with their [[behavior]]al consequences, are studied in the field of [[psychology]].
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=== Consciousness and thought ===
 
=== Consciousness and thought ===
{{details more|Consciousness|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]], [[orangutan]]s, [[dolphin]]s, and possibly [[dove|pigeons]]<ref>Robert W. Allan explores a few of these experiments on his webpage:
 
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]], [[orangutan]]s, [[dolphin]]s, and possibly [[dove|pigeons]]<ref>Robert W. Allan explores a few of these experiments on his webpage:
http://ww2.lafayette.edu/~allanr/mirror.html</ref>. In October 2006, three [[elephant]]s at the [[Bronx]] Zoo also passed this test.<ref>{{cite journal | author = | title = Self-recognition in an Asian elephant. | journal = Proc Natl Acad Sci U S A | volume = | issue = | pages = | year = | id = PMID 17075063}}</ref> Humans under the age of 2 typically fail this test.<ref>[http://www.ulm.edu/~palmer/ConsciousnessandtheSymbolicUniverse.htm Consciousness and the Symbolic Universe], by Dr. Jack Palmer, retrieved [[March 17]], [[2006]].</ref> However, this may be a matter of degree rather than a sharp divide. Monkeys have been trained to apply abstract rules in tasks.<ref>[http://web.mit.edu/newsoffice/2001/abstract-0718.html Researchers home in on how brain handles abstract thought] - retrieved [[July 29]], [[2006]]</ref>
+
[http://ww2.lafayette.edu/~allanr/mirror.html]. In October 2006, three [[elephant]]s at the [[Bronx]] Zoo also passed this test. Humans under the age of 2 typically fail this test.[http://www.ulm.edu/~palmer/ConsciousnessandtheSymbolicUniverse.htm Consciousness and the Symbolic Universe], by Dr. Jack Palmer. However, this may be a matter of degree rather than a sharp divide. Monkeys have been trained to apply abstract rules in tasks.[http://web.mit.edu/newsoffice/2001/abstract-0718.html] Researchers home in on how brain handles abstract thought].
  
 
The brain [[perception|perceives]] the external world through the [[sense]]s, and each individual human is influenced greatly by his or her experiences, leading to [[subjectivity|subjective]] views of [[existence]] and the passage of [[time]].
 
The brain [[perception|perceives]] the external world through the [[sense]]s, and each individual human is influenced greatly by his or her experiences, leading to [[subjectivity|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 [[perception|perceive]] the relationship between [[Personal identity (philosophy)|oneself]] and one's [[natural environment|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.<ref>Dennett, Daniel (1991). ''Consciousness Explained''. Little Brown & Co, 1991, ISBN 0-316-18065-3.</ref> Psychologist [[B.F. Skinner]] has argued that the mind is an explanatory fiction that diverts attention from environmental causes of behavior<ref>Skinner, B.F. About Behaviorism 1974, page 74-75</ref>. Further, that what are commonly seen as mental processes may be better conceived of as forms of covert [[Verbal Behavior]]<ref>Skinner, B.F. About Behaviorism, Chapter 7: Thinking</ref>.
+
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 [[perception|perceive]] the relationship between [[Personal identity (philosophy)|oneself]] and one's [[natural environment|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. (''Consciousness Explained''. Little Brown & Co, 1991, ISBN 0-316-18065-3). Psychologist [[B.F. Skinner]] has argued that the mind is an explanatory fiction that diverts attention from environmental causes of behavior. Further, that what are commonly seen as mental processes may be better conceived of as forms of covert [[Verbal Behavior]]
  
 
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 [[phenomenology|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]].
 
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 [[phenomenology|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]].
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=== Motivation and emotion ===
 
=== Motivation and emotion ===
 
[[Image:Goya Tio Paquete.jpg|200px|thumb|[[Goya]]'s ''Tio Paquete'' (1820).]]
 
{{details more|Motivation|Emotion}}
 
  
 
[[Motivation]] is the driving force of desire behind all deliberate [[Action (philosophy)|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 is defined by the individual brain state, which may be influenced 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.
 
[[Motivation]] is the driving force of desire behind all deliberate [[Action (philosophy)|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 is defined by the individual brain state, which may be influenced 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]] [[incentive]]s, [[moral]] incentives, or [[coercive]] incentives. Religions generally posit [[Deity|divine]] or [[demon]]ic influences.
+
Within psychology, conflict avoidance and the [[libido]] are seen to be primary motivators. Within economics motivation is often seen to be based on [[financial]] [[incentive]]s, [[moral]] incentives, or [[coercive]] incentives. Religions generally posit [[divine]] or [[demon]]ic influences.
  
 
[[Happiness]], or being happy, is a human emotional condition. The definition of happiness is a common [[philosophy|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 (philosophy)|freedom]] from want and distress; [[consciousness]] of the [[goodness and value theory|good]] order of things; assurance of one's place in the [[universe]] or [[society]], [[inner peace]], and so forth.
 
[[Happiness]], or being happy, is a human emotional condition. The definition of happiness is a common [[philosophy|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 (philosophy)|freedom]] from want and distress; [[consciousness]] of the [[goodness and value theory|good]] order of things; assurance of one's place in the [[universe]] or [[society]], [[inner peace]], and so forth.
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=== Love and sexuality ===
 
=== Love and sexuality ===
{{details more|Love|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 (according to some traditions); and in a [[hedonism|hedonistic]] sense to the enjoyment of activity involving sexual gratification. [[lust|Sexual desire]], or [[libido]], is experienced as a bodily urge, often accompanied by strong emotions such as [[love]], [[ecstasy (emotion)|ecstasy]] and [[jealousy]].
 
[[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 (according to some traditions); and in a [[hedonism|hedonistic]] sense to the enjoyment of activity involving sexual gratification. [[lust|Sexual desire]], or [[libido]], is experienced as a bodily urge, often accompanied by strong emotions such as [[love]], [[ecstasy (emotion)|ecstasy]] and [[jealousy]].
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Human sexual choices are usually made in reference to cultural [[norm (sociology)|norms]], which vary widely. Restrictions are sometimes determined by religious beliefs or social customs.
 
Human sexual choices are usually made in reference to cultural [[norm (sociology)|norms]], which vary widely. Restrictions are sometimes determined by religious beliefs or social customs.
  
Many [[Sexology|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]]).{{fact|date=November 2007}} In a variation of this, pioneering researcher [[Sigmund Freud]] believed that humans are born [[Psychosexual development|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.<ref> Buss, David M. (2004) "The Evolution of Desire: Strategies of Human Mating". Revised Edition. New York: Basic Books" </ref><ref> Thornhill, R., & Palmer, C. T. (2000). A Natural History of Rape. Biological Bases of Sexual Coercion. Cambridge: MIT Press. </ref>
+
Many [[Sexology|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 [[Psychosexual development|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.<ref> Buss, David M. (2004) "The Evolution of Desire: Strategies of Human Mating". Revised Edition. New York: Basic Books" </ref><ref> Thornhill, R., & Palmer, C. T. (2000). A Natural History of Rape. Biological Bases of Sexual Coercion. Cambridge: MIT Press.
  
 
== Culture ==
 
== Culture ==
{{Social Infobox/Human}}
 
{{details more|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]] 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 [[artifact (archaeology)|artifacts]]. A culture's [[value (personal and cultural)|values]] define what it holds to be important or [[ethics|ethical]]. Closely linked are [[norm (sociology)|norms]], expectations of how people ought to behave, bound by [[tradition]]. Artifacts, or [[archaeological culture|material culture]], are objects derived from the culture's values, norms, and understanding of the world.
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Culture consists of values, social norms, and [[artifact|artifacts]]. A culture's [[value (personal and cultural)|values]] define what it holds to be important or [[ethics|ethical]]. Closely linked are [[norm (sociology)|norms]], expectations of how people ought to behave, bound by [[tradition]]. Artifacts, or [[archaeological culture|material culture]], are objects derived from the culture's values, norms, and understanding of the world.
  
 
The mainstream [[anthropological]] view of [[culture]] implies that most people experience a strong resistance when reminded that there is an animal as well as a spiritual aspect to human nature.<ref name="AnthropologyTodayApr07" />
 
The mainstream [[anthropological]] view of [[culture]] implies that most people experience a strong resistance when reminded that there is an animal as well as a spiritual aspect to human nature.<ref name="AnthropologyTodayApr07" />
  
 
=== Language ===
 
=== Language ===
{{details more|Language}}
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The capacity humans have to transfer concepts, ideas and notions through speech and writing is unrivaled in known species. The faculty of [[Speech communication|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 [[nation]]s, [[culture]]s and [[ethnic group]]s.
 
The capacity humans have to transfer concepts, ideas and notions through speech and writing is unrivaled in known species. The faculty of [[Speech communication|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 [[nation]]s, [[culture]]s and [[ethnic group]]s.
  
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=== Art, music and literature ===
 
=== Art, music and literature ===
  
[[Image:Lorenzo Lippi 001.jpg|thumb|170px|right|''Allegory of Music'' (ca. 1594), a [[painting]] of a woman writing [[sheet music]] by [[Lorenzo Lippi]].]]
 
{{details more|Art|Music|Literature}}
 
 
Artistic works have existed for almost as long as humankind, from early [[Prehistory|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.
 
Artistic works have existed for almost as long as humankind, from early [[Prehistory|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.
  
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[[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 [[genre]]s as [[epic poetry|epic]], [[legend]], [[mythology|myth]], [[ballad]], and [[folklore]].
 
[[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 [[genre]]s as [[epic poetry|epic]], [[legend]], [[mythology|myth]], [[ballad]], and [[folklore]].
  
[[Image:7BrahmanMH.jpg|thumb|150px|left|Sculpture of a man [[meditation| meditating]].]]
+
=== Spirituality and religion ===
  
=== 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]].  
{{details more|Spirituality|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]].  
 
  
 
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 [[divinity|divine]], and the [[moral code]]s, practices, values, institutions and rituals associated with such belief. In the course of its [[development of religion|development]], religion has taken on many forms that vary by culture and individual perspective.
 
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 [[divinity|divine]], and the [[moral code]]s, practices, values, institutions and rituals associated with such belief. In the course of its [[development of religion|development]], religion has taken on many forms that vary by culture and individual perspective.
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Although a majority of humans profess some variety of spiritual or religious belief, some are [[irreligion|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]].
 
Although a majority of humans profess some variety of spiritual or religious belief, some are [[irreligion|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]].
  
[[Image:Thinker.jpg|thumb|left|150px|''[[The Thinker]]'', Artist's rendering of the sculpture by [[Auguste Rodin]].]]
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=== Philosophy and self-reflection ===
  
=== Philosophy and self-reflection ===
 
{{details more|Philosophy|Human self-reflection|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.
 
[[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.
 
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.
  
[[Image:Sanzio 01 Plato Aristotle.jpg|thumb|right|[[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 [[philosophy|philosophical]] perspective of [[cosmology (metaphysics)|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.<!-- For some reason the only two philosophies that were at all explained in this section were metaphysics and philosophy of mind. A broader, and less specific, explanation of the field is necessary. -->
 
[[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 [[philosophy|philosophical]] perspective of [[cosmology (metaphysics)|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.<!-- For some reason the only two philosophies that were at all explained in this section were metaphysics and philosophy of mind. A broader, and less specific, explanation of the field is necessary. -->
  
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=== Science and technology ===
 
=== Science and technology ===
[[Image:Apollo Moonwalk2.jpg|thumb|right|205px|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, [[space exploration|explore space]] and [[Apollo 11|walk on the moon]].]]
 
{{details more|Science|Technology}}
 
 
Science is the discovery of knowledge about the world by verifiable means. Technology is the objects humans make to serve their purposes.
 
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 [[Artifact (archaeology)|artifacts]] they produced. Early humans left [[stone tools]], [[pottery]] and [[jewelry]] that are particular to various regions and times.
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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 [[Artifact|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.
 
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.
  
[[Image:Astronaut-in-space.jpg|thumb|left|300px|Space science provides a new perspective on human significance]]
 
 
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.
 
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.
  
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=== Race and ethnicity ===
 
=== Race and ethnicity ===
{{details more|Race|Ethnic group}}
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Humans often categorize themselves in terms of [[race]] or [[ethnic group|ethnicity]], although the validity of human races as true biological categories is questionable.[http://www.nature.com/ng/journal/v36/n11s/full/ng1454.html] Human racial categories are based on both [[ancestry]] and visible [[trait (biological)|traits]], especially [[human skin color|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]].[http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=10712212] 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.[http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16175499] However, this remains an area of active debate.
Humans often categorize themselves in terms of [[race]] or [[ethnic group|ethnicity]], although the validity of human races as true biological categories is questionable.<ref>{{cite journal | author = Royal C, Dunston G | title = Changing the paradigm from 'race' to human genome variation. | url=http://www.nature.com/ng/journal/v36/n11s/full/ng1454.html | journal = Nat Genet | volume = 36 | issue = 11 Suppl | pages = S5-7 | year = 2004 | id = PMID 15508004}}</ref> Human racial categories are based on both [[ancestry]] and visible [[trait (biological)|traits]], especially [[human skin color|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]].<ref>{{cite journal | author = Risch, N., Burchard, E., Ziv, E. and Tang, H. | year = 2002 | month = | title = Categorization of humans in biomedical research: genes, race and disease | journal = Genome Biology | volume = 3 | issue = 7 | pages = comment2007.2001 - comment2007.2012 | pmid=12184798 | url = http://genomebiology.com/2002/3/7/comment/2007 }}</ref>
 
 
 
Currently available [[Genetic anthropology|genetic]] and archaeological evidence is generally interpreted as supportive of a [[recent single origin hypothesis|recent single origin]] of modern humans in [[East Africa]].<ref>{{cite journal | author = Hua Liu, et al | title = A Geographically Explicit Genetic Model of Worldwide Human-Settlement History | url = http://www.journals.uchicago.edu/AJHG/journal/issues/v79n2/43550/43550.html | journal = The American Journal of Human Genetics | volume = 79 | pages = 230–237 | year = 2006}}</ref>  Genetic studies have demonstrated that humans on the [[Africa]]n continent are most genetically diverse ([[Y-chromosome]] and [[MtDNA]] lineages).<ref>{{cite journal | author = Jorde L, Watkins W, Bamshad M, Dixon M, Ricker C, Seielstad M, Batzer M | title = The distribution of human genetic diversity: a comparison of mitochondrial, autosomal, and Y-chromosome data. | url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=10712212 | journal = Am J Hum Genet | volume = 66 | issue = 3 | pages = 979-88 | year = 2000 | id = PMID 10712212}}</ref> 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.<ref>{{cite journal | author = | title = The use of racial, ethnic, and ancestral categories in human genetics research. | url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16175499 | journal = Am J Hum Genet | volume = 77 | issue = 4 | pages = 519-32 | year = 2005 | id = PMID 16175499}}</ref> However, this remains an area of active debate.<ref>{{cite journal |author=Edwards A |title=Human genetic diversity: Lewontin's fallacy |journal=Bioessays |volume=25 |issue=8 |pages=798-801 |year=2003 |pmid=12879450}}</ref><ref>Keita, S. O. Y., Kittles, R. A., Royal, C. D. M., Bonney, G. E., Furbert-Harris, P., Dunston, D. M., and Rotimi, C. M. (2004). ''Conceptualizing human variation'': '''Nature Genetics''' 36, S17 - S20 (2004) {{doi|10.1038/ng1455}}</ref>
 
  
 
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]].
 
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 ==
 
== Society ==
{{details more|Society}}
 
  
 
[[Society]] is the system of organizations and institutions arising from interaction between humans.
 
[[Society]] is the system of organizations and institutions arising from interaction between humans.
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=== Government and politics ===
 
=== Government and politics ===
  
[[Image:United Nations HQ - New York City.jpg|thumb|right|The [[United Nations]] complex in [[New York City]], which houses one of the largest human political organizations in the world.]]
 
{{details more|Government|Politics|State}}
 
 
A [[state]] is an organized [[politics|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."<ref>[http://www.mdx.ac.uk/www/study/xweb.htm Max Weber's definition of the modern state 1918], by [[Max Weber]], 1918, retrieved [[March 17]], [[2006]].</ref>
 
A [[state]] is an organized [[politics|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."<ref>[http://www.mdx.ac.uk/www/study/xweb.htm Max Weber's definition of the modern state 1918], by [[Max Weber]], 1918, retrieved [[March 17]], [[2006]].</ref>
  
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All of these issues have a direct relationship with [[economics]].
 
All of these issues have a direct relationship with [[economics]].
 
[[Image:Nagasakibomb.jpg|left|thumb|The [[atomic bombings of Hiroshima and Nagasaki]] immediately killed over 120,000 people.]]
 
  
 
=== War ===
 
=== War ===
{{details more|War}}
 
 
War is a state of widespread [[conflict]] between [[state]]s, [[organization]]s, or relatively large groups of people, which is characterized by the use of lethal [[violence]] between [[combatant]]s or upon [[civilian]]s. It is estimated that during the 20th century between 167 and 188 million humans died as a result of war.<ref>Ferguson, Niall. "The Next War of the World." Foreign Affairs, Sep/Oct 2006</ref>
 
War is a state of widespread [[conflict]] between [[state]]s, [[organization]]s, or relatively large groups of people, which is characterized by the use of lethal [[violence]] between [[combatant]]s or upon [[civilian]]s. It is estimated that during the 20th century between 167 and 188 million humans died as a result of war.<ref>Ferguson, Niall. "The Next War of the World." Foreign Affairs, Sep/Oct 2006</ref>
  
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=== Trade and economics ===
 
=== Trade and economics ===
  
[[Image:Market-Chichicastenango.jpg|thumb|right|230px|Buyers and sellers bargain in [[Chichicastenango]] Market, [[Guatemala]].]]
 
{{details more|Trade|Economics}}
 
 
[[Trade]] is the voluntary exchange of [[good (accounting)|goods]], [[Service (economics)|service]]s, or both, and a form of [[economics]]. A mechanism that allows trade is called a [[market]]. The original form of trade was [[barter (economics)|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 (finance)|credit]], paper money and non-physical money) greatly simplified and promoted trade.
 
[[Trade]] is the voluntary exchange of [[good (accounting)|goods]], [[Service (economics)|service]]s, or both, and a form of [[economics]]. A mechanism that allows trade is called a [[market]]. The original form of trade was [[barter (economics)|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 (finance)|credit]], paper money and non-physical money) greatly simplified and promoted trade.
  
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== External links ==
 
== External links ==
{{Commonscat|Homo sapiens}}
 
 
* [http://www.mnsu.edu/emuseum/biology/humanevolution/sapiens.html MNSU]
 
* [http://www.mnsu.edu/emuseum/biology/humanevolution/sapiens.html MNSU]
 
* [http://www.archaeologyinfo.com/homosapiens.htm Archaeology Info]
 
* [http://www.archaeologyinfo.com/homosapiens.htm Archaeology Info]
 
* [http://www.breitbart.com/article.php?id=070824121653.65mgd37f Chororapithecus abyssinicus] Possible human-orangutan split 20 million years ago. (Aug 26 2007)
 
* [http://www.breitbart.com/article.php?id=070824121653.65mgd37f Chororapithecus abyssinicus] Possible human-orangutan split 20 million years ago. (Aug 26 2007)
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 +
[[Category: Anthropology]]
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[[Category: General Reference]]

Revision as of 16:34, 3 September 2010

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History

Origin

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 human"), the other known subspecies, is extinct. [1] Anatomically modern humans appear in the fossil record in Africa about 130,000 years ago.[2]




see the documentary film: Becoming Human


The closest living relatives of Homo sapiens are two distinct species of the genus Pan: the Bonobo (Pan paniscus) and the Common Chimpanzee (Pan troglodytes). These species 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, 95 per cent of the DNA sequence is identical between the two Pan species and human.Frans de Waal, Bonobo ISBN 0-520-20535-9 [3] [4] [5][6]| 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. [7]

The Recent African Origin (RAO), 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. Evidence from Archaeogenetics accumulating since the 1990s has lent strong support to RAO and has marginalized the competing multiregional hypothesis, which proposed that modern humans evolved, at least in part, from independent hominid populations. [8]

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. They also propose 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, one of those is the Toba catastrophe theory.

Human evolution is characterized by a number of important morphological, developmental, physiological and behavioral changes which have taken place since the split between the last common ancestor of Homo and Pan. The primary change, both in terms of chronology and in terms of it being the trait that defines the human subtribe the Hominina, was the evolution of a bipedal locomotor adaptation from an arboreal or semi-arboreal locomotor adaptation, with all its attendant adaptations, such as a valgus knee, low intermembral index (long legs relative to the arms) and reduced upper body strength. Following this was the evolution of a larger brain cavity and brain itself, which is typically 1,400 cm³ in modern humans; over twice that of a chimpanzee or gorilla. Other significant morphological changes included: the evolution of a power and precision grip; a reduced masticatory system; a reduction of the canine tooth; and the descent of the larynx and hyoid bone, making speech possible. With respect to development, 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. One important physiological change in humans was the evolution of hidden estrus or concealed ovulation in females, which may have coincided with the evolution of important behavioral changes, such as pair bonding. Another significant behavioral change includes the development of material culture, or the (over time) increasingly wide variety of human-made objects which are used to manipulate humans' physical and social environments. How all these changes are related and what their role is in the evolution of complex social organization and culture are matters of ongoing debate.(How Humans Evolved, ISBN 0-393-97854-0]

Rise of civilization

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 inhabited Eurasia and Oceania by 40,000 BP, and finally inhabited the Americas approximately 10,000 years ago. "Out of Africa again and again" They displaced Homo neanderthalensis and other species descended from Homo erectus (which had inhabited Eurasia as early as 2 million years ago) through more successful reproduction and competition for resources.

Up until only around 10,000 years ago, all humans lived as hunter-gatherers (with some communities persisting until this day). They generally lived in small, nomadic groups. The advent of agriculture prompted the Neolithic Revolution. Access to food surplus 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 Judaism, originating in the Middle East, and Hinduism, a religious tradition that originated in South Asia, 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

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. 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; however, humans have made robots that have visited other celestial bodies.

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,[9] 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.'Scientific American Evolution and General Intelligence: Three hypotheses on the evolution of general intelligence. Currently, through land development and pollution, humans are thought to be the main contributor to global climate change. [10] 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.[1]

Biology

Physiology and genetics

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. Britannica Concise Encyclopedia. Encyclopædia Britannica, Inc., 2006. [11] Humans are capable of fully bipedal locomotion, thus leaving their arms available for manipulating objects using their hands, aided especially by opposable thumbs.

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.Cite error: Closing </ref> missing for <ref> tag While one in five Europeans is 60 years of age or older, only one in twenty Africans is 60 years of age or older. [The World Factbook]

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.[2] 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 accompanied 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. A pure animal diet can, for instance, lead to scurvy, while a pure plant 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 plant diet.[12] However, according to American Dietetic Association and the Dietitians of Canada, properly planned vegetarian and vegan diets are nutritionally adequate and healthy.[13]

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.[3] Childhood malnutrition is also common and contributes to the global burden of disease. 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 Centers for Disease Control (CDC) state 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,[4] 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

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.[5] 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. 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. Even the most ancient human tools and structures are far more advanced than any structure or tool created by any other animal.[6]

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".[7]

Consciousness and thought

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 pigeonsCite error: Closing </ref> missing for <ref> tag Phenomenal consciousness is the state of being conscious, such as when they 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

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 is defined by the individual brain state, which may be influenced 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. These were commonly developed 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

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 (according to some traditions); 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.[8]Cite error: Closing </ref> missing for <ref> tag

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.

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.[9]

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. Full scale pitched-battle wars between adversaries of comparable strength appear to have nearly disappeared from human activity, with the last major one in the Congo region winding down in the late 1990's. Nearly all war now is asymmetric warfare, in which campaigns of sabotage, guerrilla warfare and sometimes acts of terrorism disrupt control and supply of better-equipped occupying forces, resulting in long low-intensity wars of attrition.

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, and ethnic cleansing. Military intelligence has often played a key role in determining victory and defeat. Propaganda, which often includes factual information, slanted opinion and disinformation, plays a key role in maintaining unity within a warring group, and/or sowing discord among opponents. 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 technology. Throughout history there has been a constant struggle between defense and offense, for example between armour and the weapons designed to breach it. Modern examples include the bunker buster bomb, and the bunkers which they are designed to destroy. Important inventions such as medicine, navigation, metallurgy, mass production, nuclear power, rocketry and computers have been completely or partially driven by war.

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 tradeable commodity, or because different regions' size allows for the benefits of mass production.

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.

External links

  1. American Association for the Advancement of Science. Foreword. AAAS Atlas of Population & Environment. Wilson, E.O. (2002). in The Future of Life.
  2. U.N. Statistics on Population Ageing, United Nations press release, February 28, 2002, retrieved April 2, 2005
  3. Death and DALY estimates for 2002 by cause for WHO Member States World Health Organisation. Accessed 29 Oct 2006
  4. Earliest agriculture in the Americas Earliest cultivation of barley Earliest cultivation of figs - URLs retrieved February 19, 2007
  5. 3-D Brain Anatomy, The Secret Life of the Brain, Public Broadcasting Service, retrieved April 3 2005.
  6. Sagan, Carl (1978). The Dragons of Eden. A Ballantine Book. ISBN 0-345-34629-7
  7. Jonathan Benthall Animal liberation and rights Anthropology Today Volume 23 Issue 2 Page 1 - April 2007
  8. Buss, David M. (2004) "The Evolution of Desire: Strategies of Human Mating". Revised Edition. New York: Basic Books"
  9. Ferguson, Niall. "The Next War of the World." Foreign Affairs, Sep/Oct 2006