Milk and Rice, Freedom and Despotism
Commenting on the study and noting that "Northwestern Europe comprises difficult land for growing crops, but grows grass abundantly," Steve Sailer analyzes that "[w]ithout dairying, the population density would have stayed low outside the rich river valleys" — Lactose tolerance hotspots.
The only other part of the globe to develop comparable levels of culture, East Asia, lies outside these "lactose tolerance hotspots" (and some pretty backward regions lie within), so, how did these East Asians do it without milk (but how did lactose tolerant West Africans, Arabians, and whatever Pakistanis used to be fail so miserably with milk)?
Rice. The paddy, specifically. Franklin Hiram King's 1911 tome, Farmers of Forty Centuries: Organic Farming in China, Korea, and Japan (originally titled Farmers of Forty Centuries; Or, Permanent Agriculture in China, Korea, and Japan), explains how rice cultivation allowed population density to grow outside rich river valleys and civilization to develop in these great countries long, long before Europe was anything to speak of.
However, as Karl August Wittfogel's 1957 tome, Oriental Despotism: A Comparative Study of Total Power, explains, rice cultivation, with its paddies requiring extensive levees and irrigation ditches, necessitates a high degree of collectivism and centralization, i.e. despotism, in comparison to the freewheeling individualism of dairymen and cattlemen.
Maybe milk and rice explain in part how the two advanced cultural regions of the globe developed differently.