Editing Brown (section)

=== Brown skin ===
A majority of people in the world have skin that is a shade of brown, from a very light honey brown or a golden brown, to a copper or bronze color, to a coffee color or a dark chocolate brown. Skin color and race are not the same; many people classified as "white" or "black" actually have skin that is a shade of brown. Brown skin is caused by [[melanin]], a natural pigment which is produced within the skin in cells called [[melanocyte]]s. Skin pigmentation in humans evolved to primarily regulate the amount of [[ultraviolet radiation]] penetrating the skin, controlling its biochemical effects.<ref name=jabl1>{{cite book|last=Muehlenbein|first=Michael|title=Human Evolutionary Biology|year=2010|publisher=Cambridge University Press|pages=192–213}}</ref>

Natural skin color can darken as a result of [[Sun tanning|tanning]] due to exposure to sunlight. The leading theory is that skin color adapts to intense sunlight irradiation to provide partial protection against the [[ultraviolet radiation|ultraviolet]] fraction that produces damage and thus mutations in the [[DNA]] of the skin cells.<ref name=pmid20445093>{{cite journal |last1=Jablonski |first1=N. G. |last2=Chaplin |first2=G. |title=Colloquium Paper: Human skin pigmentation as an adaptation to UV radiation |journal=Proceedings of the National Academy of Sciences |volume=107 |pages=8962–8 |year=2010 |issue=Suppl 2 |doi=10.1073/pnas.0914628107 |pmid=20445093 |pmc=3024016 |bibcode=2010PNAS..107.8962J|doi-access=free }}</ref> There is a correlation between the geographic distribution of ultraviolet radiation (UVR) and the distribution of indigenous skin pigmentation around the world. Darker-skinned populations are found in the regions with the most ultraviolet, closer to the equator, while lighter skinned populations live closer to the poles, with less UVR, though immigration has changed these patterns.<ref name=webb06>{{cite journal|last=Webb|first=A.R.|title=Who, what, where, and when: influences on cutaneous vitamin D synthesis|journal=Progress in Biophysics and Molecular Biology|volume=92|issue=1|pages=17–25|pmid=16766240|year=2006|doi=10.1016/j.pbiomolbio.2006.02.004|doi-access=}}</ref>

While ''white ''and'' black'' are commonly used to describe racial groups, ''[[Brown (racial classification)|brown]]'' is rarely used, because it crosses all racial lines.
In [[Brazil]], the Portuguese word ''[[pardo]]'', which can mean different shades of brown, is used to refer to multiracial people. The Brazilian Institute of Geography and Statistics (IBGE) asks people to identify themselves as ''branco'' (white), ''pardo'' (brown), ''negro'' (black), or ''amarelo'' (yellow). In 2008 43.8 percent of the population identified themselves as pardo.<ref>IBGE. 2008 PNAD. [http://www.sidra.ibge.gov.br/bda/tabela/protabl.asp?c=262&i=P&nome=on&notarodape=on&tab=262&unit=0&pov=1&opc1=1&poc2=1&OpcTipoNivt=1&opn1=2&nivt=0&orc86=3&poc1=1&orp=6&qtu3=27&opv=1&poc86=2&sec1=0&opc2=1&pop=1&opn2=0&orv=2&orc2=5&qtu2=5&sev=1000093&opc86=1&sec2=0&opp=1&opn3=0&sec86=0&sec86=2776&sec86=2777&sec86=2779&sec86=2778&sec86=2780&sec86=2781&ascendente=on&sep=43344&orn=1&qtu7=9&orc1=4&qtu1=1&cabec=on&pon=1&OpcCara=44&proc=1&opn7=0&decm=99 População residente por cor ou raça, situação e sexo].</ref> (See [[human skin color]]).
<gallery mode="packed" heights="150px">
File:Elderly Gambian woman face portrait.jpg|An elderly woman from Gambia
File:Flickr - DavidDennisPhotos.com - Man at Ruins in Cairo.jpg|A man from Egypt
File:Gisele Bundchen2 cropped.jpg|A woman from Brazil
File:Sera Monastery13.jpg|A man from Tibet
File:Peruvian woman in hat smiling.jpg|A young woman from Peru
</gallery>