Melanin levels in African populations

[EDsomali]

Khoi-San in Botswana are the lightest African group.

A big difference between Nilo-Saharans from Tanzania and Ethiopia.

Source

 

[World]

Why would they group Ethiopia Cushitic and Tanzania "Cushitic" together?

 

[Apollo]

Silly categories, the Iraqw have Bantu and Hadza admixture and are not the same as Horn Cushites.

Also, Omotics are quite diverse. Shekkacho/Wolaytas (North Omotics) are very different from the Hamar and other South Omotics.

 

[Timo Jareer and proud]

I thought Berbers where the lightest

 

[EDsomali]

I thought Berbers where the lightest

Sub-Saharan groups sxb.

 

[Timo Jareer and proud]

Sub-Saharan groups sxb.

Oh okay so no cheating then. I thought Tigrinya would be the lightest but okay

 

[EDsomali]

Oh okay so no cheating then. I thought Tigrinya would be the lightest but okay

Environmental pressures are probably the reason why.

 

[Apollo]

 

[World]

Environmental pressures are probably the reason why.

They highly selected for light skin after contact with Cushitic nomads. Here’s the study:

“Skin pigmentation is under strong directional selection for reduced melanin density in northern European and Asian populations. Conversely, dark pigmentation is thought to be under stabilizing selection in equatorial populations exposed to intense ultraviolet radiation. We high-throughput sequenced pigmentation genes in over 400 individuals from South Africa and demonstrate that a canonical skin pigmentation gene, SLC24A5, experienced recent adaptive evolution in the KhoeSan populations of far southern Africa. The functionally caustive allele lightens basal skin pigmentation by 4 melanin units, explaining 11.9% variance in pigmentation in these populations. Haplotype analysis and demographic models indicate that the allele was introduced into the KhoeSan only within the past 3,000 years likely by eastern African pastoralists. The most common haplotype is shared among the KhoeSan, eastern Africans and Europeans but has risen to a frequency of 25%, far greater than expected given initial gene flow. The SLC24A5 locus is a rare example of strong, ongoing adaptation in very recent human history.”

https://meeting.physanth.org/progra...ter-skin-pigmentation-in-southern-africa.html

 

[911]

They highly selected for light skin after contact with Cushitic nomads. Here’s the study:

“Skin pigmentation is under strong directional selection for reduced melanin density in northern European and Asian populations. Conversely, dark pigmentation is thought to be under stabilizing selection in equatorial populations exposed to intense ultraviolet radiation. We high-throughput sequenced pigmentation genes in over 400 individuals from South Africa and demonstrate that a canonical skin pigmentation gene, SLC24A5, experienced recent adaptive evolution in the KhoeSan populations of far southern Africa. The functionally caustive allele lightens basal skin pigmentation by 4 melanin units, explaining 11.9% variance in pigmentation in these populations. Haplotype analysis and demographic models indicate that the allele was introduced into the KhoeSan only within the past 3,000 years likely by eastern African pastoralists. The most common haplotype is shared among the KhoeSan, eastern Africans and Europeans but has risen to a frequency of 25%, far greater than expected given initial gene flow. The SLC24A5 locus is a rare example of strong, ongoing adaptation in very recent human history.”

https://meeting.physanth.org/progra...ter-skin-pigmentation-in-southern-africa.html

So they selected for light skin but kept their peppercorn hair?

 

[World]

So they selected for light skin but kept their peppercorn hair?

I have no idea why tbh, maybe there wasn’t any benefit to having straight or wavy hair so it wasn’t selected for?

 

[911]

I have no idea why tbh, maybe there wasn’t any benefit to having straight or wavy hair so it wasn’t selected for?

Yeah tbh, maybe they just didnt have a preference for it, but what was the benefit of lighter skin?

 

[World]

Yeah tbh, maybe they just didnt have a preference for it, but what was the benefit of lighter skin?

Melanin reduces the skin’s ability to make vitamin D in response to sunlight exposure. So the Khoisan in South Africa heavily selected for it.

Btw there is another gene responsible for skin pigmentation which is more important than what Horners have and that is the derived G allele at SLC45A2's rs16891982 SNP. Proto-Cushites did have it, but selected against it because it probably gave them skin cancer or some shit, meaning we selected for more pigmentation. Even the habeshas who got more recent admixture from south arabians(who have it) the last 2000 years selected against it.