Experiments with primitive technology - A hobby reminiscent of our slave prehistoric ancestors ?

Slavery may have been common among prehistoric peoples even before agriculture / horticulture.

The need for disposable (sold or killed) workforce existed even among hunter-gatherers.

Read  "Slaves, chiefs and labour on the northern Northwest Coast", Kenneth M. Ames, in World Archaeology Vol. 33(1): 1-17 The Archaeology of Slavery
 http://web.pdx.edu/~amesk/pdfs/slaves_World_Arch.pdf

Digesting milk : is it in the genes or in the gut bacteria ?

First time I finally read that gut bacteria (and not genetic traits) could be what helps humans digest milk.

OK, I'm wildly interpreting this article : http://www.upenn.edu/pennnews/news/penn-team-links-africans-ability-digest-milk-spread-cattle-raising, about a study led by University of Pennsylvania researchers on genes and lactase persistence in African populations. It ends with "Another possibility is that commensal bacteria in the gut could offer humans a helping hand in digesting milk."

My guess