The system just ate a long post of mine, brilliantly refuting post point by point because it said I wasn’t logged in. How could I be logged in on every other thread except this one? Mods, what gives?
All right. I will pull my shattered nerves together and try again.
My argument is a specific one, using specific circumstances on a specific population. I do not say that milk drinking = white skins, but that white skins and milk drinking evolved symbiotically in these circumstances. That outcome will not develop in places where these circumstances do not apply.
First, milk does not have to come from cattle, and historically seldom did. Goats, sheep, mares, yaks, camels, and many other animals were used for dairying. There are even distinct names for the otherwise identical fermented milks made from different animals’ milks. The horse cultures made extensive use of mare’s milk. The Mongols even developed the first dried milk, which powder could be carried with them and later reconstituted with water into a thin milk.
Several lines of evidence, including the spread of the Indo-European languages, appear to show that the farmers who moved north and then west across Europe (and also west and then north, i.e. through Greece, Rome and Spain), stem from areas near the Caucasus region. They are ancestral, but the peoples there today do not have the same level of lactose tolerance or whiteness of skin tone as say the Scandinavians. Whiteness is a continuum, not a state of being. But of course they were European. White skins change nothing about that.
The several tribes along the fringes of the Sahara and the Sahal are also a fascinating case of peoples who became milk drinkers through selection pressures. They were herders in areas in which hardly any other food source exists. Naturally those who could drink milk as adults had an advantage. But they lived near the equator and spent their lives outdoors. Why would they need to select for lightness of skin when they got all the vitamin D they needed by exposing their skin to the sun.
Asians are too large a category to pigeonhole. The Chinese, in dense populations, choose the pig rather than grazing animals as their primary meat source. Pigs are not milkable. The Chinese had to get their calcium from other sources, soybeans, e.g. Those farther west did have cattle and better tolerated milk. Indians had cattle and did indeed use their milk. Yogurt and cheese are common items in the Northern Indian cooking, areas which also were influenced by Indo-European speaking peoples. Southern Indians had different food sources and did not need the extra nutrients they could get from milk.
There is no need at all to posit that 5000 years separates Northern Europeans from Africans. As I said, they are descended from peoples elsewhere who had many more thousands of years of separation from African populations. Interestingly, present day Semitic populations have lactose tolerance levels halfway between northern Europeans and eastern Asians.
I admitted that I shortened a complex set of arguments, but there are answers for all the other groups you mention. They just have nothing to do with the particulars of the one case. Harris (who died earlier this year) was probably the foremost anthropological authority on the effect that food had on culture. He also wrote a great many books for the popular audience, some of which cover the other areas I’ve gone into here. In addition to the one mentioned above, an interesting source is the chapter “The Origin of the Sacred Cow” in Cannibals and Kings. There are other writers on the subject as well, although you need to do some digging into the anthro literature to find them.