[jrapdx3]

Based on prior discussions I've had the impression that the BNC2 and other skin-related Neanderthal genes were associated with less melanin pigmentation.

Melanin reduces penetration of UVB into skin cells, important in an equatorial environment to protect skin integrity. However in northerly latitudes, heavily pigmented skin is a disadvantage due to the role of UVB exposure in producing vitamin D, essential to survival.

Indeed the most pigmented skin requires 5 times the UVB exposure to produce equivalent amount of vitamin D vs. least pigmented. A possible tradeoff for adaptating to an environment with less available sunlight is greater susceptibility to developing conditions like melanoma, but that's admittedly an oversimplification of a very complex subject.