Enlarge / Researchers extracted DNA from the remains of people buried in the East Smithfield plague pits, which were used for mass burials in 1348 and 1349. (credit: Museum of London Archaeology)
When the Black Death massacred up to 50 percent of the European population in the mid-14th century, it appears to have etched an enduring mark on human genetics, altering the frequency of genes that shape our immune systems—which may or may not be a good thing for modern humans.
That's according to a study out Wednesday in Nature from an international team of researchers led by anthropologists and geneticists at McMaster University in Canada and the University of Chicago.
The team dug deep into genetic data from over 200 people who died prior to the Black Death, during the deadly pandemic, and afterward in London and Denmark. Their findings suggest that the pandemic was a selective evolutionary pressure on humans, shifting the diversity of gene variants for at least four immune system-related genes. Subsequent petri-dish experiments with immune cells suggested that variants of the four genes were protective against the plague bacteria—Yersinia pestis—as well as other pathogens. But the authors also note that some of the genes have been associated with an increased risk of autoimmune diseases, such as Crohn's disease, rheumatoid arthritis, and lupus.
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