Well, Iain Mathieson is kind of a big deal in this area, I would be inclined to back his point of view; I wouldn't be too surprised if the field does switch to mostly backing his point of view in time. When we talk about how we find "none of the genes driving light skin" we mean that we find none of the genes driving light skin in recent West Eurasian people and of course East Asian people also lack these variants (but have light skin).
We don't find the East Asian skin colour genes in WHGs either. What we find are varieties of the skin influencing genes that are associated with dark skin across todays population varieties.
There are likely other solutions for light skin that we don't understand yet, and there's still quite a bit of missing unexplained heritability of skin phenotype even within West Eurasian populations - when Mathieson says that there are variants that are likely to have been lost, he's saying this from a point of view of being a Harvard geneticist at the cutting edge of ancient dna and phenotype prediction, and that probably carries a bit more weight than you or I.
Note Lazaridis's objections are "But a Eur. Mesolithic ind. with present-day light-skin mutations from a high latit. would most likely also be light-skinned, no?" is not a dismissal of variants being present that we don't know about, rather that the variants we do know about should lead to the same outcome.
Which actually is what I am saying. We do know that there were variants for dark skin present, we should not assume totally speculative evidence countering that. To me, Lazaridis is also pointing out the essential hypocrisy in immediately assuming that the presence of known skin-lightening variants means individuals were European-style white while the presence of known skin darkening variants means there must have been some unknown other factor present lightening the skin.
Lazaridis also says "WHG may have had unknown skin-lightening alleles; but it'd be strange if light skin remained a stable phenotype with a switch of the underlying genes.", but of course, that's not particularly so as it would've been exactly the case if say present day Europeans replaced an unrelated East Asian related Siberian population with light skin.
But its not a population replacement, it is a mixing. And a stable phenotype with a replacement of the dirving genes is the opposite of how we'd expect things to go.
(Even within trying to naively apply existing models, there is significant variance implied on skin colour for different WHG individuals -
https://www.biorxiv.org/content/10.1101/267443v1 - "
We also analysed two previously-published WHGs, and find potential temporal and/or geographical variation in pigmentation characteristics. Loschbour from Luxembourg is ~2000 years younger than Cheddar Man, and is predicted to have had intermediate skin pigmentation. Furthermore, the Loschbour individual most likely had blue/green eyes. In contrast, La Braña from northern Spain who is slightly later than Loschbour is predicted to have had dark to dark to black skin and hazel/green eye colour. Both La Braña and Loschbour were predicted to have had black, possibly dark brown hair. These results imply that quite different skin pigmentation levels coexisted in WHGs at least by around 6000 BC.")
Well that is precisely what we'd expect, isn't it? We have more light-skinned Eastern Hunter-Gatherers (EHG) and people from the Caucasus migrating in and mixing with the WHG, and we find that specimens further to the east and more recent in time end up lighter. And once again, we can't really argue that the presence of intermediate and lighter varieties mean they were intermediate or light while maintaining that the presence of darker varieties means we cannot predict their pigmentation.
And -appeal to authority fallacy. I do admit that Mathieson knows far more about the subject than me. My degree was decades in the past, and I did not do much relevant work in similar fields after graduation. I have started skipping the methods sections of papers, and the statistics programs they have available these days are beyond me. I am pretty much willing to swallow any adequate argument Mathieson makes as long as it is not totally unbelievable. Which is where the problem lies, as the argument is not adequate and the statement not really believable.
It is like you graduated from computing a few decades ago and read about a respected computer expert sating "
We should not expect that we will be able to build a computer with a larger single-memory than 160 Terabytes because there may be issues we've never seen before and which we have no indication may exist, that will make it impossible" It would raise eyebrows.
The thing is, arguing that we cannot assume that people were black just because they have most of the gene varieties that lead to black skin in all the rest of the populations of the world, because there may have been genes affecting that that we've never seen and vanished before we could, and do not show up anywhere else -that argument is weak. It would be weak if God made it. And that is before we take into consideration that as Lazaridis points out, it is not advanced when we find light skin associated genes in a population. Now this is a very controversial area, and its drawn the ire of some very extroverted people with an emotional investment in their ancestral skin varieties. IfyouknowthesortImean. And to me this "
Well we can't really know actually because, uh, reasons" feels far more like an attempt to calm the waters than anything else.
There are already tools developed to automate the process of determining pigmentation from samples, which were
developed for forensics.
UV reflected by snow could damage eyes (snow blindness) and light eyes are more prone to damage than dark ones. So why blue eyes?
We don't know. We know that a strong north-south cline have persisted through thousands of years of population movement, indicating very heavy selection. But not why.
Also, Tibet is one thing, but Hokkaido, northern Honsiu, Korea are also snowy places located in Mediterranean lattitudes (Mediterranean Europe is not that far south, in places not affected by Golfstrom at the same lattitudes temperatures are much lower, especially in winter). Native Americans also are not Andamanese-like, but their ancestors crossed Asia during Ice Age.
That is one thing. Another is the fact, that Neanderthals (who occupied Europe for much o time than AMH and were cold adapted people) are known to have red/ blond hair.
The blonde bit is new to me? I do know of the red hair one (MC1R ottomh) but it seems mostly associated with freckling in terms of pigmentation. As far as North Asians go, it would generally be biologically cheaper to retain a melanistic trait than to redevelop it.I think a better argument would be that Siberia towards the end of the Ice Age is where we see the first serious increases in the European type light pigmentation genes.