Admittedly a biased source but it's the only link I've found at short notice:
http://www.beefyandlamby.co.uk/red-meat.html One thing we can be sure of. Meat made up a substantial portion of the ancient human diet in Europe. Also I recall that modern vitamin D deficiency does occur in black-skinned people in Europe these days but only in those whose culture demands they cover up in an unnatural manner. Selection for white skin is unlikely to have anything to do with vit. D.
Re. colour change in domesticated animals. I've been aware of the fox phenomenon for some years. Many of the genes were probably already present as recessives in the wild population. They have been able to survive as double recessives through lack of selection pressure. In the wild there is an advantage for animals to look much the same as each other. Any that stand out are likely to be predated quickly. Likewise for animals that are less afraid. Once a colour variation is established in a domestic population there is no selection to eliminate it. The question for hair colour variation in humans is who domesticated them? Was it each other?
I agree totally with the idea that dogs entered human society on their own initiative.
