Editing Hair (section)

===Evolutionary variation===
Primates are relatively hairless compared to other mammals, and [[Hominini]] such as chimpanzees, have less dense hair than would be expected given their body size for a primate.<ref name="Sandel 2013 pp. 145–150">{{cite journal |last=Sandel |first=Aaron A. |date=2013-07-30 |title=Brief communication: Hair density and body mass in mammals and the evolution of human hairlessness |journal=American Journal of Physical Anthropology |volume=152 |issue=1 |pages=145–150 |doi=10.1002/ajpa.22333 |pmid=23900811 |issn=0002-9483|hdl=2027.42/99654 |hdl-access=free }}</ref> Evolutionary biologists suggest that the genus ''[[Homo]]'' arose in [[East Africa]] approximately 2 million years ago.<ref name="Herries Martin Leece Adams 2020 p.">{{cite journal |last1=Herries |first1=Andy I. R. |last2=Martin |first2=Jesse M. |last3=Leece |first3=A. B. |last4=Adams |first4=Justin W. |last5=Boschian |first5=Giovanni |last6=Joannes-Boyau |first6=Renaud |last7=Edwards |first7=Tara R. |last8=Mallett |first8=Tom |last9=Massey |first9=Jason |last10=Murszewski |first10=Ashleigh |last11=Neubauer |first11=Simon |last12=Pickering |first12=Robyn |last13=Strait |first13=David S. |last14=Armstrong |first14=Brian J. |last15=Baker |first15=Stephanie |date=2020-04-03 |title=Contemporaneity of ''Australopithecus'' , ''Paranthropus'' , and early ''Homo erectus'' in South Africa |journal=Science |volume=368 |issue=6486 |page= |doi=10.1126/science.aaw7293 |issn=0036-8075 |last16=Caruana |first16=Matthew V. |last17=Denham |first17=Tim |last18=Hellstrom |first18=John |last19=Moggi-Cecchi |first19=Jacopo |last20=Mokobane |first20=Simon |last21=Penzo-Kajewski |first21=Paul |last22=Rovinsky |first22=Douglass S. |last23=Schwartz |first23=Gary T. |last24=Stammers |first24=Rhiannon C. |last25=Wilson |first25=Coen |last26=Woodhead |first26=Jon |last27=Menter |first27=Colin|pmid=32241925 |doi-access=free }}</ref> Part of this evolution was the development of [[Endurance running hypothesis|endurance running]]<ref name="Ruxton Wilkinson 2011 pp. 169–175">{{cite journal |last1=Ruxton |first1=Graeme D. |last2=Wilkinson |first2=David M. |year=2011 |title=Thermoregulation and endurance running in extinct hominins: Wheeler's models revisited |journal=Journal of Human Evolution |volume=61 |issue=2 |pages=169–175 |doi=10.1016/j.jhevol.2011.02.012 |pmid=21489604 |bibcode=2011JHumE..61..169R |issn=0047-2484}}</ref> and venturing out during the hot times of the day<ref name="Ruxton Wilkinson 2011 pp. 20965–20969">{{cite journal |last1=Ruxton |first1=Graeme D. |last2=Wilkinson |first2=David M. |date=2011-12-12 |title=Avoidance of overheating and selection for both hair loss and bipedality in hominins |journal=Proceedings of the National Academy of Sciences |volume=108 |issue=52 |pages=20965–20969 |doi=10.1073/pnas.1113915108 |pmid=22160694 |pmc=3248486 |bibcode=2011PNAS..10820965R |issn=0027-8424|doi-access=free }}</ref> that required efficient thermoregulation through [[perspiration]]. The loss of heat through [[heat of evaporation]] by means of [[sweat gland]]s is aided by air currents next to the skin surface, which are facilitated by the loss of body hair.<ref name="Jablonski06">{{cite book |author=Jablonski, Nina G. |url=https://books.google.com/books?id=EYi9S3VtIGsC&pg=PP13 |title=Skin: A Natural History |date=1 May 2008 |publisher=University of California Press |isbn=978-0-520-94170-0 |pages=13– |access-date=27 January 2016}}</ref>

Another factor in human evolution that also occurred in the prehistoric past was a preferential selection for [[neoteny]], particularly in females. The idea that adult humans exhibit certain neotenous (juvenile) features, not evinced in the other great apes, is about a century old. [[Louis Bolk]] made a long list of such traits,<ref>{{Cite book|last=Bolk|first=L.|year=1926|title=Das Problem der Menschwerdung|publisher=Fischer|location=Jena|language=de}}</ref> and [[Stephen Jay Gould]] published a short list in ''[[Ontogeny and Phylogeny (book)|Ontogeny and Phylogeny]]''.<ref>short-list of 25 characters reprinted in Gould, Stephen Jay (1977). ''[[Ontogeny and Phylogeny (book)|Ontogeny and phylogeny]]''. Harvard University Press. p. 357. {{ISBN|0674639413}}.</ref> In addition, [[paedomorphic]] characteristics in women are often [[Physical attractiveness#Determinants of female physical attractiveness|acknowledged as desirable by men]] in developed countries.<ref>{{cite journal |last1=Scott|first1= Isabel M.|date=7 October 2014 |title=Human preferences for sexually dimorphic faces may be evolutionarily novel |journal=Proceedings of the National Academy of Sciences of the United States of America|volume=111 |issue=40 |pages= 14388–14393|doi=10.1073/pnas.1409643111 |pmid= 25246593|pmc= 4210032|bibcode=2014PNAS..11114388S|doi-access= free}}</ref> For instance, [[vellus hair]] is a juvenile characteristic. However, while men develop longer, coarser, thicker, and darker [[terminal hair]] through [[sexual differentiation]], women do not, leaving their vellus hair visible.
{{further|Human evolutionary genetics}}