...
Post A Reply
my profile
|
directory
login
|
register
|
search
|
faq
|
forum home
»
EgyptSearch Forums
»
Deshret
»
Some interesting articles
» Post A Reply
Post A Reply
Login Name:
Password:
Message Icon:
Message:
HTML is not enabled.
UBB Code™ is enabled.
[QUOTE]Originally posted by DD'eDeN: [QB] https://anthropology.net/2017/10/12/on-the-evolution-of-skin-tones-in-africa/ Evolutionary geneticist Sarah Tishkoff of the University of Pennsylvania, the lead author of the new study measured the reflectance of light on the skin of 2,092 people from Ethiopia, Tanzania, and Botswana along with Nicholas Crawford. The eastern African groups, like the Mursi and Surma, had the darkest skin on objective reflectance assessments, and the lightest are the San with shades between such as the Agaw. Concurrently, they collected blood samples of 1,570 of these people for genetic studies and sequenced more than 4 million SNPs. They found 8 sites of the human genome that are particularly associated with the level of skin pigmentation which makes up for 30% of the variation in skin tone we see. Four key areas of the genome, which emerged 900,000 years ago, have specific SNPs that correlate directly with skin color. SLC24A5, that gene I commented on before, and that we’ve known about for over 12 years to be associated with lighter skin tones, is common in some Ethiopian populations. Variants of this gene appeared 30,000, likely from Middle Eastern groups returning to eastern Africa. Variants of two neighboring genes, HERC2 and OCA2, which are also associated with light skin, eyes, and hair phenotypes seen in Europeans ultimately arose in Africa. The SNPs we see in Europeans are ancient and common in the light-skinned San people. The team proposes that these SNPs arose in Africa over 1 million years ago and spread later to Europeans and Asians. Which is incredible and I’ll comment on later. I think the most dramatic discovery is of MFSD12. Two SNPs which decrease expression of this gene were found in high frequencies in people with the darkest skin. They confirmed in culture cells that these mutant MFSD12 genes lead to more eumelanin. These variants arose about a 500,000 years ago, suggesting that human ancestors before that time may have had moderately dark skin, rather than the deep black hue created today by these mutations. These same two variants are found in Melanesians, Australian Aborigines, and some Indians, which implies that these groups may have inherited the variants from ancient migrants from Africa who followed a “southern route” out of East Africa, along the southern coast of India to Melanesia and Australia. The latest findings suggest that some particularly dark skin tones evolved relatively recently from paler genetic variants, and these people migrated out of Africa. SNPs in OCA2 and HERC2 that are associated with lighter skin are ancient, over 1 million years old and come from Africa. [/QB][/QUOTE]
Instant Graemlins
Instant UBB Code™
What is UBB Code™?
Options
Disable Graemlins in this post.
*** Click here to review this topic. ***
Contact Us
|
EgyptSearch!
(c) 2015 EgyptSearch.com
Powered by UBB.classic™ 6.7.3