London’s East Smithfield Cemetery made news this week because of a recent study suggesting that the Medieval Black Death provided impetus for human evolution in a way that shapes many of our genomes today.
With the advent of technology that allows for whole genome analysis of the dead, scientists and historians decided to exhume skeletons in East Smithfield that had been buried shortly before, during, and after the mid-14th century outbreak of the bubonic plague. This particular pandemic (which became known as the Black Death) was the most severe in recorded history, with 33-50% of Europeans dying.
In a study published in the journal _Nature_ this week, a team of DNA analysts discovered that survivors of the 1348-1349 plague had gene variants that helped them resist the Yersinia pestis, the bacterium that causes plague.
A variant of a gene called ERAP2 was particularly important — it works with the human immune system to help recognize Yersinia pestis. The cemetery results indicate that only 40% of Londoners had the protective variant of ERAP2 before the pandemic. Of those who died in the fateful Black Death, only 35% had the variant. And within a few generations, 50% of Londoners had the protective version of ERAP2.
These numbers are actually quite a big deal, and, if results are replicated elsewhere, it would mean the Black Death changed humanity’s gene pool faster than any other known agency. 45% of British people today still have that protective variant.
However, there is a downside to this protection: this version of ERAP2 is associated with a higher risk of autoimmune diseases like Crohn’s Disease and rheumatoid arthritis.
Source: _Science_ “How the Black Death changed our immune systems,” Ann Gibbons, 19 Oct 2022. _Nature_ “Evolution of immune genes is associated with the Black Death,” 19 Oct 2022, Klunk et al, Photo from the Museum of London Archaeology
