> “Certain kinds of farming practices, particularly the very traditional ones, have this extraordinary protective effect in the sense that, in these communities, asthma and allergies are virtually unknown,” said Donata Vercelli, a professor of cellular and molecular medicine at the University of Arizona. “The studies that have been done in these farming populations are critical because they tell us that protection is an attainable goal.”
Larger challenges to the immune system, and perhaps those who could not handle this load died off or left over the generations? Selection pressure should be familiar to those in CS.
Too clean, or not too clean: the Hygiene Hypothesis and home hygiene - https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2222...