This may be better explained by the Hygiene hypothesis - hunter-gatherers get exposure to all sorts of microbes and parasites early in their life while city-dwe

This may be better explained by the Hygiene hypothesis - hunter-gatherers get exposure to all sorts of microbes and parasites early in their life while city-dwellers could be shielded from equivalent exposure. See: https://en.wikipedia.org/wiki/Hygiene_hypothesis https://en.wikipedia.org/wiki/Hygiene_hypothesis