Comments on: Expert Resolutions to Skin Problems Affecting African American Women http://www.womenhealthline.com/skin-problems/ Tue, 06 Dec 2011 11:56:27 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: vareeja http://www.womenhealthline.com/skin-problems/#comment-7216 vareeja Thu, 24 Jun 2010 12:05:45 +0000 http://www.womenhealthline.com/?p=1998#comment-7216 A matter of fact- five million years ago the human ancestors' dark hair protected their light skin from the intense African sun so that there was no evolutionary constraint that killed off the progeny of those who had mutations in the MC1R nucleotide sequences that made their skin light. However, over 1.2 million years ago, judging from the numbers and spread of variations among human and chimpanzee MC1R nucleotide sequences, the human ancestors in Africa began to lose their hair and they came under increasing evolutionary pressures that killed off the progeny of individuals who retained the inherited lightness of skin. Folate breakdown in sun-exposed skin is inhibited by the presence of melanin, and folate is essential for human fetal development. It is likely that folate conservation played an important role in the selection of dark skin in the ancient African ancestors of modern humans. By 1.2 million years ago, all people having descendants today had exactly the receptor protein of today's Africans; their skin was dark, and the intense sun killed off the progeny with any lighter skin that resulted from mutational variation in the receptor protein. A matter of fact- five million years ago the human ancestors’ dark hair protected their light skin from the intense African sun so that there was no evolutionary constraint that killed off the progeny of those who had mutations in the MC1R nucleotide sequences that made their skin light.

However, over 1.2 million years ago, judging from the numbers and spread of variations among human and chimpanzee MC1R nucleotide sequences, the human ancestors in Africa began to lose their hair and they came under increasing evolutionary pressures that killed off the progeny of individuals who retained the inherited lightness of skin. Folate breakdown in sun-exposed skin is inhibited by the presence of melanin, and folate is essential for human fetal development. It is likely that folate conservation played an important role in the selection of dark skin in the ancient African ancestors of modern humans.

By 1.2 million years ago, all people having descendants today had exactly the receptor protein of today’s Africans; their skin was dark, and the intense sun killed off the progeny with any lighter skin that resulted from mutational variation in the receptor protein.

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