[_heimdall]

It'd be interesting to see more data that could help narrow down potential factors in the difference of gut microbes.

Highly processed foods and use of prescription drugs (especially antibiotics) come to mind. I could see both of those being different for rural vs urban populations and would likely have some impact on microbiomes.

[lambdaba]

Also birth by c-section https://www.science.org/content/article/swabbing-c-section-b... "The microbiomes of C-section babies look a lot different from those of babies born vaginally. In particular, they have lower numbers of Lactobacillus, Escherichia, and Bacteroides bacteria in their guts."