A Paper Dedicated to Microbes That Cause Infectious Diseases
Scholars examined a large number of ancient human remains in order to detect ancient microbes. They concluded that the shift to farming — and especially to pastoralism — increased the prevalence of infectious diseases. Cohabitation with livestock appears to have been the main cause of this increase.
In Europe, the mass migration from the steppe around 3000 BC coincides with a peak in microbial DNA detected in ancient remains. The authors propose that steppe pastoralists, who relied heavily on livestock, developed greater immunity to certain zoonotic diseases than European farmers, who depended primarily on crop cultivation. This may help explain the population changes observed in Europe.
Below is an excerpt from their conclusion:
“We observed some of the highest detection rates at roughly 5,000 bp, a time of substantial demographic changes in Europe due to the migration of Steppe pastoralists and the displacement of earlier populations. Steppe pastoralists, through their long-term continuous exposure to animals, probably developed some immunity to certain zoonoses, and their dispersals may have carried these diseases westwards and eastwards. Consequently, the genetic upheaval in Europe could have been facilitated by epidemic waves of zoonotic diseases causing population declines, with depopulated areas subsequently being repopulated by opportunistic settlers who intermixed with the remaining original population. This scenario would mirror the population decline of Indigenous peoples in the Americas following their exposure to diseases introduced by European colonists. Our findings support the interpretation of increased pathogen pressure as a likely driver of positive selection on immune genes associated with the risk of multiple sclerosis in Steppe populations roughly 5,000 years ago, and immune gene adaptations having occurred predominantly after the onset of the Bronze Age in Europe.”
