http://www.sciencemag.org/news/2015/04/how-europeans-evolved-white-skinOf course those samples predate CWC, C'mon, but they aren't nearly as phenotypically fair, nor as LCT positive as modern Europeans, much less modern North Europeans. That is what I'm speaking to as it relates to the discussion of blondism, which you only see in high frequencies in modern North Europe. We only begin to see anything close to this after CWC, in populations that look to descend from CWC like genotypes e.g. Andronovo, Shintasha, Srubnaya, and Nordic Bronze Age (along with BB related groups like the Raithlin samples).
This is why I'm saying that it looks like it's happening in or around CWC genotypes as we move through the bronze age. This also comes along with elevated LCT frequencies, which why I'm theorizing that it was the combination of LCT and fair traits that was really being selected for rather than one or the other.
I'm getting more and more convinced of this, so I welcome criticism, but we need something like this to explain this explosion of features that are ultra-fair in comparison to the rest of the world. I do think that this genotype in dairying populations offers such a cause.
You have these alleles floating around in these populations, probably from ancient selection events, but they don't seem to really be increasing in frequency all that much for thousands of years. Then all of sudden these alleles, along with LCT, increase drastically right around the time when stock breeding, and presumably dairying, becomes prevalent.
"But in the far north—where low light levels would favor pale skin—the team found a different picture in hunter-gatherers: Seven people from the 7700-year-old Motala archaeological site in southern Sweden had both light skin gene variants, SLC24A5 and SLC45A2. They also had a third gene, HERC2/OCA2, which causes blue eyes and may also contribute to light skin and blond hair. Thus ancient hunter-gatherers of the far north were already pale and blue-eyed, but those of central and southern Europe had darker skin.
Then, the first farmers from the Near East arrived in Europe; they carried both genes for light skin. As they interbred with the indigenous hunter-gatherers, one of their light-skin genes swept through Europe, so that central and southern Europeans also began to have lighter skin. The other gene variant, SLC45A2, was at low levels until about 5800 years ago when it swept up to high frequency."
there is something else i found quite interessting:
"They found that selection strongly favored several gene variants for tallness in northern and central Europeans, starting 8000 years ago, with a boost coming from the Yamnaya migration, starting 4800 years ago. The Yamnaya have the greatest genetic potential for being tall of any of the populations, which is consistent with measurements of their ancient skeletons. In contrast, selection favored shorter people in Italy and Spain starting 8000 years ago, according to the paper now posted on the bioRxiv preprint server. Spaniards, in particular, shrank in stature 6000 years ago, perhaps as a result of adapting to colder temperatures and a poor diet."
that last sentence makes no real sense in my opinion. how was spain colder than central and northern europe.
here is the full study about the topic
https://www.biorxiv.org/content/biorxiv/early/2015/03/13/016477.full.pdf
so the frequency of those alleles for skin, eye and hair color did increase in the last few thousand years in every population. but it was already high in SHGs way before CWC.