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Author Topic: First Irish populations had dark skin similar to Cheddar Man, DNA research suggests
tropicals redacted
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"IT’S LIKELY THAT the early Irish populations had dark skin, similar to the Cheddar Man discovery made in the UK this week, according to genetic experts.

This week, UK scientists confirmed that the first modern Briton had dark skin and blue eyes, following groundbreaking DNA analysis of the remains of a man who lived 10,000 years ago.

Known as Cheddar Man, after the area in southwest England where his skeleton was discovered in a cave in 1903, the ancient made had been brought to life through the first ever full DNA analysis of his remains.

The findings of the joint project between Britain’s Natural History Museum and University College London transformed the way people had previously seen Cheddar Man, who had been portrayed as having brown eyes and light skin in an earlier model.

Speaking on RTÉ Radio One’s Morning Ireland, professor of population genetics at Trinity College Dublin, Dan Bradley said that a project with the National Museum of Ireland has made similar findings for that of the earliest Irish populations.

The researchers working on the Irish project have compiled data from two individuals from over 6,000 years ago that provide similar results as Cheddar Man.

“The earliest Irish would have been the same as Cheddar Man and would have had darker skin than we have today,” Bradley said.

He said their findings suggest the DNA is linked to individuals from Spain and Luxembourg, people who populated western European after the last Ice Age but before the farming era.

Similarly, Cheddar Man’s tribe migrated to Britain at the end of the last Ice Age and his DNA has been linked to individuals discovered in modern-day Spain, Hungary and Luxembourg.

“We think [the Irish examples] would be similar. The current, very light skin we have in Ireland now is at the endpoint of thousands of years of surviving in a climate where there’s very little sun,” Bradley said.

“It’s an adaptation to the need to synthesise vitamin D in skin. It has taken thousands of years for it to become like it is today.”

Bradley’s research suggests that there were about 30-40,000 people on the island of Ireland at the time that the dark skin genomes date back to.

“They came here very probably by boat. They ate a lot of fish, hunted wild boar, gathered plants and nuts,” he said.

Bradley said that the team of scientists at Trinity College Dublin hope to have their research fully completed within the year."

http://www.thejournal.ie/cheddar-man-irish-dark-skin-3840186-Feb2018/

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xyyman
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Am I right or am I right?

Europeans were black up to about 5000 years ago. They were essentially Dravidian/Australians/Melanesians. The irony is light skin alleles probably always existed in Africa(Tanzania area) but became prolific with the spread of farmers starting in the Great Lakes region of Africa. Keep in mind Some Kenyan groups carry as much of 30% SLC24A5


This is what the data shows!

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Without data you are just another person with an opinion - Deming

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Ase
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But when did it spread in the Middle East? It would've spread there first and then Europe. How much sooner did that happen?
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Thereal
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It doesn't need to spread if the mutation occurred independently in whatever population,it's only a thing because how close Europe, Asia and Africa are and some of these earlier groups similar or the same genetically.
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capra
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didn't occur independently. same exact mutation happening twice on same haplotype background in multiple cases - extremely unlikely.

the skin colour alleles people mostly refer to are rs1426654 (SLC24A5) and rs16891982 (SLC45A2). both were present in Northern Europe and West Asia even before the Neolithic. we don't know where they originated or how they spread but it would have been back in the Palaeolithic.

keep in mind these account for only a small proportion of the variation in human skin colour. i don't know if Cheddar Man's skin colour prediction is based on extensive coverage of known pigmentation genes or is just the same old few. hopefully the former, but if the latter then we don't really know if he was particularly dark-skinned, and have no reason to think he was 'black'.

Kotias and Satsurblia, 2 hunter-gatherers from Georgia (about 11 200 BC and 9700 BC), both had 2 copies of derived SLC24A5 allele. in Scandinavia both derived alleles were common 6000-7000 BC or earlier, and also found in Russia around 5500 BC. so again we don't know for sure but it seems there were some quite light-skinned, blue-eyed, and maybe red- or blond-haired people already in Mesolithic Sweden, probably among a range of skin tones.

the early farmers of northwestern Anatolia (~6500-6200 BC) had 100% of derived SLC24A5 allele and ~40% derived SLC45A2 allele. these are thought to be pretty close to the ancestral population of the farmers who started colonizing Europe a little before 6000 BC. (They already had ~35% of the 'blue eye' allele in HERC2 as well). Early Central and Southern European farmers seem pretty much the same. hard to say exactly what they looked like but i'd guess olive skin (mostly on the darker side), dark hair, and mostly dark eyes.

so yes there is pretty strong evidence that Europeans have got lighter over time - and part of it may even have to do with population movements 5000 years ago - but the known genetic ingredients have been present for at least 8000 years, and some proportion in combinations that would make for 'white' skin.

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xyyman
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BS! Capra. yes, SLC45A2 seems to have left Africa with the first OOA Keep in mind black Melanesians carry derived SLC45A2...and yes they are black. Howver they lack SLC24A5. And we have the reverse with Kenyans who carry SLC24A5 derived but low frequency of SLc45A2. Apparently BOTH allele are needed along with maybe other genes. So no!!! Europeans weren't white 5000years ago. Stop BSing!

@Oshun. The DNA of Bronze age Levantine and early Neolithic North Africans has been revealed and they carry the ancestral form of the alleles for black skin ie they were black like Africans.

Quote: by the fantasy novelist SMH. Did you dream up those color yourself? SMH
: "
"Early Central and Southern European farmers seem pretty much the same. hard to say exactly what they looked like but i'd guess olive skin (mostly on the darker side), dark hair, and mostly dark eyes."

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Without data you are just another person with an opinion - Deming

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the lioness,
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http://science.sciencemag.org/content/358/6365/eaan8433

Loci associated with skin pigmentation identified in African populations

Sarah A. Tishkoff et al 2017

Structured Abstract
INTRODUCTION
Variation in pigmentation among human populations may reflect local adaptation to regional light environments, because dark skin is more photoprotective, whereas pale skin aids the production of vitamin D. Although genes associated with skin pigmentation have been identified in European populations, little is known about the genetic basis of skin pigmentation in Africans.
RATIONALE
Genetically and phenotypically diverse African populations are informative for mapping genetic variants associated with skin pigmentation. Analysis of the genetics of skin pigmentation in Africans informs upon melanocyte biology and the evolution of skin pigmentation in humans.
RESULTS
We observe extensive variation in skin pigmentation in Africa, with lowest melanin levels observed in southern African San hunter-gatherers and highest levels in East African Nilo-Saharan pastoralists. A genome-wide association study (GWAS) of 1570 Africans identified variants significantly associated with skin pigmentation, which clustered in four genomic regions that together account for almost 30% of the phenotypic variation.

The most significantly associated single-nucleotide polymorphisms were at SLC24A5, a gene associated with pigmentation in Europeans. We show that SLC24A5 was introduced into East Africa >5 thousand years ago (ka) and has risen to high frequency.

The second most significantly associated region is near the gene MFSD12. Using in vitro and in vivo analyses, we show that MFSD12 codes for a lysosomal protein that modifies pigmentation in human melanocytes, with decreased MFSD12 expression associated with darker pigmentation. We also show that genetic knockouts of MFSD12 orthologs affect pigmentation in both zebrafish and mice.

A third highly associated region encompasses a cluster of genes that play a role in ultraviolet (UV) response and DNA damage repair. We find the strongest associations in a regulatory region upstream of DDB1, the gene encoding damage-specific DNA binding protein 1, and that these variants are associated with increased expression of DDB1. The alleles associated with light pigmentation swept to near fixation outside of Africa due to positive selection, and we show that these lineages coalesce ~60 ka, corresponding with the time of migration of modern humans out of Africa.

The fourth significantly associated region encompasses the OCA2 and HERC2 loci. We identify previously uncharacterized variants at HERC2 associated with the expression of OCA2. These variants arose independently from eye and skin pigmentation–associated variants in non-Africans. We also identify variants at OCA2 that are correlated with alternative splicing; alleles associated with light pigmentation are correlated with a shorter transcript, which lacks a transmembrane domain.
CONCLUSION
We identify previously uncharacterized genes and variants associated with skin pigmentation in ethnically diverse Africans. These genes have diverse functions, from repairing UV damage to playing important roles in melanocyte biology. We show that both dark and light pigmentation alleles arose before the origin of modern humans and that both light and dark pigmented skin has continued to evolve throughout hominid history. We show that variants associated with dark pigmentation in Africans are identical by descent in South Asian and Australo-Melanesian populations. This study sheds light on the evolutionary history, and adaptive significance, of skin pigmentation in humans.

_________________________________

https://www.theatlantic.com/science/archive/2017/10/a-brief-history-of-the-genes-that-color-our-skin/542694/

Atlantic

The Ancient Origins of Both Light and Dark Skin
A study of diverse people from Africa shows that the genetic story of our skin is more complicated than previously thought.

(excerpt)

But most of the variants that Tishkoff’s team identified, for both light and dark skin, have an ancient African origin. They likely arose in hominids like Homo erectus long before the dawn of our own species, and have coexisted in balance for hundreds and thousands of years. In many cases, the older variant is responsible for lighter skin, not darker. That’s consistent with an idea from Nina Jablonski, an anthropologist from Pennsylvania State University, who thinks that the ancient ancestors of humans—much like other primates—had pale skin. “As our ancestors moved out of the forest and into the savannah, they lost their hair and evolved darker skin,” says Nick Crawford, a researcher in Tishkoff’s lab.

But that wasn’t an all-encompassing change. Different groups of people adapted to their own particular environments, not just around the world, but within Africa, too. “Africa is not some homogenous place where everyone has dark skin,” Tishkoff says. “There’s huge variation.” For example, her team’s measurements showed that the Nilotic peoples in eastern Africa have some of the darkest skin around, while the San of southern Africa have light skin, comparable to some East Asians.

This physical diversity is mirrored in these groups’ genes. The first gene identified as affecting human skin color—MC1R—is very diverse in European populations but remarkably similar across African ones. Based on that pattern, says Tishkoff, some geneticists have concluded that the evolutionary pressure for dark skin in Africa is so strong that any genetic variants that altered skin color were ruthlessly weeded out by natural selection. “That’s not true,” says Tishkoff—but it’s what happens when you only study skin color in Western countries. “When you look at this African-centered perspective, there’s a lot of variation.”

For example, a gene called MFSD12 has variants that are linked to darker skin; these are common in dark-skinned people from East Africa, but rare among the lighter-skinned San. MFSD12 also shows how the search for pigmentation genes can reveal new insights about the basic biology of our skin. Two years ago, the gene didn’t even have a name, but it was linked to vitiligo—a condition where people develop white patches on dark skin. By deleting the gene in fish and mice, Tishkoff’s colleagues confirmed that it controls the balance between light and dark pigments.

Another gene called SLC24A5 has a variant that has traditionally been seen as “European,” because it is so starkly associated with lighter skin in Western European populations. But Tishkoff’s team showed that the variant entered the East African gene pool from the Middle East several millennia ago and well before the era of colonization. Today, it is common in Ethiopian and Tanzanian groups, but rare in other areas.

“The study really discredits the idea of a biological construct of race.”
Critically, in East African groups, the variant doesn’t lighten skin color to the same degree that it does in Europeans. It’s a stark reminder that “a person can carry a gene that confers a particular trait in one population and yet not obviously show evidence of that trait themselves,” says Jablonski.

:

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xyyman
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Thanks you Lioness. I forgot to add that the gene is on the same Loci for Europeans and Africans. I rest my case.


quote:
Originally posted by the lioness,:
http://science.sciencemag.org/content/358/6365/eaan8433

Loci associated with skin pigmentation identified in African populations

Sarah A. Tishkoff et al 2017

:



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Without data you are just another person with an opinion - Deming

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capra
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both those alleles are thought to post-date Out-of-Africa. this is psychologically unacceptable to xyyman of course but that is a matter for your shrink.

anyway i think the skin colour thing is beaten to death, we won't know more till further high quality aDNA comes out, or maybe someone will have a look for the newly discovered alleles in old data. for now it's pretty much eh who knows.

PS "gene is on the same loci" sometimes i forget just how incredibly ignorant you are. holy shit.

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xyyman
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yeah! yeah! You want me to "quote mine" ala Swenet. Prove you wrong! SMH


Huh? Post date OOA? WTF are you talking about Capra. Derived SLC45A2 is found in Papuans …and Pygmies!!!

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Without data you are just another person with an opinion - Deming

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Ish Geber
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“Loci associated with skin pigmentation identified in African populations”.


As we knew all along and has now been reconfirmed.
quote:


Although the lineage containing this haplotype must have originated in Africa, C3 is rare in Africa (1.0% in MKK) but widely distributed in East Asia, the New World, and Oceania.

[...]

Frequencies display strong population differentiation, with the derived light skin pigmentation allele (A111T) fixed or nearly so in all European populations and the ancestral allele predominant in sub-Saharan Africa and East Asia (Lamason et al. 2005; Norton et al. 2007).

[...]

Phased haplotypes were retrieved from HapMap, Release 21. For phylogenetic analysis, graphs were drawn by the use of a simple nearest-neighbor approach and rooted by the use of ancestral alleles determined by comparison with other primate sequences.

[...]

"Of the remaining 10 common core haplotype groups, all ancestral at rs1426654, eight clearly have their origins in Africa (Figure 3B, Figure 4, and Table S4). Three early diverging haplotypes, C1, C2, and C4, are rare outside of Africa and clearly originated there."

"In the lineage containing the majority of haplotypes, each of the three branches, containing C5, C6-C7, and C8-C11, give strong evidence of having originated in Africa. C5 reaches its greatest abundance in West Africa and is rare outside of Africa. Within the other two branches, C6 and C9, which are the most common haplotypes in Africa, are also common worldwide, whereas C7 is abundant in East Asia and much less common but widespread in Africa. "

[...]

Our dating for this haplotype is consistent with a non-African origin. The most likely location for the origin of C11 is, therefore, within the region in which it is fixed or nearly so. As both models for the origin of C11 imply that C3 and C10 were present in ancestors of Europeans, the observed and inferred distributions of these autosomal haplotypes are consistent with the single-out-of- Africa hypothesis derived using uniparental markers (Oppenheimer 2003; Macaulay et al. 2005).

~Victor A. Canfield et al.
Molecular Phylogeography of a Human Autosomal Skin Color Locus Under Natural Selection 2013

Posts: 22234 | From: האם אינכם כילדי הכרית אלי בני ישראל | Registered: Nov 2010  |  IP: Logged | Report this post to a Moderator
   

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