"The adoption of agriculture is assumed to be accompanied by a diet depleted in micro-nutrients and vitamin D [Larsen, 2006, Carrera-Bastos et al., 2011]. It is highly likely that this increased the selective pressure already present for the pigmentation phenotype....Signs of non-neutrality for variants in the gene SLC24A5 indicate selection for the gene. The majority of derived alleles located in this gene were already present at high frequencies in the early farmers of this data set. It appears that strong directional selection affected these variants shortly after humans adopted farming. In contrast, a much higher variation was still present in the hunter-gatherers groups, probably due to the higher vitamin D content in their diet."
Genetic variation related to the adaptation of humans to an agriculturalist lifestyle
by Jens Blocher of Mainz, 2019, biology Ph.D. thesis
PWNOMEGA
Voidisyinyang Voidisyinyang how the fuck does your diet determine your skin tone? Here's a little bit of advice, take anything you hear on "studies" with a grain of salt.
"light skin was for many thousand years not essential for survival at higher latitudes of Europe84. In addition, there is no mechanistical link between vitamin D and the expression of the main light skin alleles, such as primary vitamin D target genes carrying VDR binding sites in their regulatory regions85. In summary, there is no convincing evidence of a direct evolutionary effect of vitamin D on skin lightening of Europeans."
"However, archeogenomic data indicated that Europeans got pale as predominant skin color just some 5000 years ago through interbreeding with migrating populations originating from Anatolia and the Russian steppe. The latter populations likely accumulated the light skin alleles via genetic drift24 rather than through an effect of vitamin D."
Skin colour and vitamin D: An update
First published: 03 July 2020
Skin depigmentation in northwestern Europe occurred gradually, over many millennia, with the introduction of the classic SLC24A5 variant being the last and most dramatic step in the process after the introduction of agriculture.
The rise and expansion of agriculture from Anatolia and Iran saw incursions of agriculturalists into southern and central Europe, increasingly displacing earlier hunter-gatherer populations (Skoglund & Mathieson, 2018). The evolution of skin pigmentation genes and phenotypes of the region reflects these dramatic movements, and the influence of relatively few genes of major effect transmitted over long distances by admixture (Ju & Mathieson, 2020). Of these, the effect of the classic depigmentation variant of SLC24A5 is greatest, with recent evidence showing that this variant reached western Europe by admixture from Anatolian agriculturalists followed by continued positive selection (Ju & Mathieson, 2020).
there's a new discovery called "epigenetics" - so that there is environmental effects that can be passed on to off spring. So it's not just genetics at all. "light skin variant derives from a single carrier who lived 22,000-28,000 years ago in the Middle East. Thus, the classic light phenotype of Europeans became frequent only within the past 5000 years and owes its origin to migrants from Near East and western Asia."
"The gene that causes lighter skin pigmentation, SLC24A5, was introduced from eastern African to southern African populations just 2,000 years ago. Strong positive selection caused this gene to rise in frequency among some KhoeSan populations."
So it spread from West Asia to East Africa via pastoral farming - and then to South Africa KoeSan.
"The gene, which is also present in people from the Near East and eastern Africa, was probably initially brought into the region by only a small number of individuals.
The actual source of the positive selection is not clear. The researchers theorize that a shift from consuming vitamin D-rich marine animals to consuming pasture animals, or a reduction in exposure to ultraviolent rays, might have changed skin pigmentation over time."
"Armand wrote that in the spring of 2005. In December of that year a paper was published in Science, SLC24A5, a Putative Cation Exchanger, Affects Pigmentation in Zebrafish and Humans. The authors concluded that:
"Based on the average pigmentation difference between European-Americans and African-Americans of about 30 melanin units, our results suggest that SLC24A5 explains between 25 and 38% of the European-African difference in skin melanin index.
SLC24A5 is manifested in disjoint polymorphisms in Africans and Europeans. At one location on this gene where almost all Europeans have an adenine, almost all Africans have a guanine."
The A variant is derived, while the G is ancestral. That is, a mutation from G → A occurred at some point in the past, and A increased in frequency in a subset of the world's populations. When did the increase in frequency occur? It seems fairly recently, Voight et. al. picked up a signature of selection around SLC24A5 though it is nearly fixed in Europeans and so is not an ideal target for their methods (which tend to be best at detecting partial sweeps). This would imply a time scale of less than 10,000 years. Another researcher has reported that the SNPs around SLC24A5 imply a selective event as recent as 5,800 years before the present! "
"Loss of skin pigmentation allowed better calciol [Vitamin D] synthesis in the
skin when man transitioned from fisherman and hunter to
farmer, an existence associated with fewer dietary sources of
preformed vitamin D. Two variants of SLC24A5 exist—
virtually all Africans and East Asians had one allele, 98%of
Europeans studied had the other. The data indicate a selective
sweep occurred 5300 to 6000 years ago resulting in European
depigmentation.35,36"
I agree with you that the EYE Color is definitely African albinos that were living in Europe. I have green eyes so I am definitely part AFRICAN albino. But the scientists have found ancient DNA that is BLUE eyes but DARK skin. So the eye color was BEFORE the "depigmentation" from the WHEAT monoculture farming that lacks vitamin D that spread across Europe about 5000 BCE. So the African-Europeans had dark skin and albino eye color - but they ate fish and liver organs to get vitamin D.
I realize there are albino africans and albino dravidians, etc. but the DNA for albino skin is not the same DNA as wheat depigmentation DNA - it's just ONE amino acid difference to change the skin color from the dark skin for sun to the malnutrition diet skin color depigmentation!
Also farming created weaker body - that's why the farmers in Spain are so short - the Basque people are the "original" farmers.
It's the Yamnaya who took over Europe around 3500 BCE - using Cattle and Milk - as pastoralists. So they were already depigmented from earlier Wheat farmers but they moved up to central europe and the Steppes of Central Asia - and then the took over Europe. So that's the tall Yamnaya but they are depigmented since they started out as wheat farmers. Just as the Berbers in North Africa are DEPigmented -
I visited the MOST traditional Berber village in North Africa - the women grew all the food from HUManure to fertilize the desert - using Humanure Compost - to grow WHEAT for thousands of years and so they were DEpigmented.
thanks
also there are studies of Europeans showing HOW much Yamnaya dna they have compared to West Asian Farming dna they have. And so the Europeans with more Yamnaya pastoral Milk DNA are taller.
No comments:
Post a Comment