A Cheesy View of History

Lactose intolerance percentage (ideonexus.com)

UC-Merced professor Justin Cook theorizes that economic development occurred earlier in the West because of Europeans' ability to digest milk [bold added].

A one-standard-deviation increase in the incidence of lactase persistence, in turn, was associated with a 40% rise in population density. People who could digest milk, the theory goes, used resources more efficiently than those who couldn’t. They could extract liquid energy from livestock, in addition to the wool, fertiliser, ploughing power and meat for which others raised them. The white stuff may have helped in other ways too: its fats, proteins, vitamins and minerals added balance to the pre-colonial diet, reducing the incidence of disease. If used as a substitute for breast-feeding, animal milk could have reduced weaning time and, thus, the time between mothers’ pregnancies. All this suggests that milk-guzzling societies could support higher population densities...

When people are tightly bunched together, the theory goes, growth takes off. Rulers find it easier to build infrastructure and administer the law, including property rights. Cities can develop, which allows workers to specialise. Technological innovation explodes; bigger armies can defend what is produced. Small wonder, then, that places with high population density in pre-colonial times tend to be relatively rich today.

Whether or not "lactase persistence" led to population density which led to industrialization has little current relevance, since regions of very high lactose intolerance have today's most populous cities (Shanghai, Karachi, Delhi, Beijing, etc.) and are struggling to catch up with First-World living standards.

Nevertheless, it is interesting that energy efficiency, whether biological or mechanical, has been a measure of societal advancement throughout history.