Editing Pygmy peoples (section)

== Short stature ==
{{See also|Short stature|Human height}}
Various theories have been proposed to explain the short stature of pygmies. Some studies suggest that it could be related to adaptation to low [[ultraviolet]] light levels in [[rainforest]]s.<ref>{{cite journal |doi=10.1002/ajpa.21512 |title=Indirect evidence for the genetic determination of short stature in African Pygmies |date=2011 |last1=Becker|first1=Noémie S.A.|last2=Verdu|first2=Paul|last3=Froment|first3=Alain|last4=Le Bomin|first4=Sylvie|last5=Pagezy|first5=Hélène|last6=Bahuchet|first6=Serge|last7=Heyer|first7=Evelyne |journal=American Journal of Physical Anthropology |volume=145 |issue=3 |pages=390–401 |pmid=21541921 |url=https://deepblue.lib.umich.edu/bitstream/2027.42/86961/1/21512_ftp.pdf |hdl=2027.42/86961 |hdl-access=free}}</ref><ref>{{cite web |title=Ultraviolet light levels in the rainforest |first=Julian |last=O'Dea |date=December 21, 2009 |url=http://julianodea.blogspot.com/2009/12/ultraviolet-light-levels-in-rainforest.html |archive-url=https://web.archive.org/web/20160304104530/http://julianodea.blogspot.com/2009/12/ultraviolet-light-levels-in-rainforest.html |archive-date=2016-03-04}}<!-- data originally published in "a newsletter put out by the Australasian Society for Human Biology". Probably very similar to below cited reference by same author. --></ref> This might mean that relatively little [[vitamin D]] can be made in human skin, thereby limiting [[calcium]] uptake from the diet for bone growth and maintenance and leading to the evolution of the small skeletal size.<ref name=o>{{Cite journal |last=O'Dea |first=JD |title=Possible contribution of low ultraviolet light under the rainforest canopy to the small stature of Pygmies and Negritos |journal=Homo: Journal of Comparative Human Biology |volume=44 |issue=3 |pages=284–7 |date=January 1994}}</ref>

Other explanations include lack of food in the rainforest environment, low calcium levels in the soil, the need to move through dense jungle, adaptation to heat and humidity, and as an association with rapid reproductive maturation under conditions of early mortality.<ref>{{Cite web |author-link=Ed Yong |last=Yong |first=Ed |date=19 December 2007 |title=Short lives, short size – why are pygmies small? |website=Not Exactly Rocket Science |url=http://notexactlyrocketscience.wordpress.com/2007/12/19/short-lives-short-size-why-are-pygmies-small/ |archive-url=https://web.archive.org/web/20120324140524/http://notexactlyrocketscience.wordpress.com/2007/12/19/short-lives-short-size-why-are-pygmies-small/ |archive-date=2012-03-24}}</ref> Other evidence points towards unusually low levels of expression of the genes encoding the [[growth hormone receptor]] and [[growth hormone]] compared to the related tribal groups, associated with low serum levels of [[insulin-like growth factor 1]] and short stature.<ref name='Bozzola, 2009'>{{cite journal | title = The shortness of Pygmies is associated with severe under-expression of the growth hormone receptor | journal = Mol Genet Metab | date = November 2009 |last1=Bozzola |first1=M |last2=Travaglino |first2=P |last3=Marziliano |first3=N |last4=Meazza |first4=C |last5=Pagani |first5=S |last6=Grasso |first6=M |last7=Tauber |first7=M |last8=Diegoli |first8=M |last9=Pilotto |first9=A |last10=Disabella |first10=E |last11=Tarantino |first11=P |last12=Brega |first12=A |last13=Arbustini |first13=E | volume = 98 | issue = 3 | pages = 310–3 | pmid=19541519 | doi=10.1016/j.ymgme.2009.05.009}}
{{Cite journal |vauthors=Dávila N, Shea BT, Omoto K, Mercado M, Misawa S, Baumann G |title=Growth hormone binding protein, insulin-like growth factor-I and short stature in two pygmy populations from the Philippines |journal=J Pediatr Endocrinol Metab |date=March 2002 |volume=15 |issue=3 |pages=269–276|doi=10.1515/JPEM.2002.15.3.269 |pmid=11924928 |s2cid=30556010 }}</ref>