On October 19, 2022, Nature published the findings of a research team from the University of Chicago, MacMaster University and the Institut Pasteur. They had extracted DNA samples from bones of over 200 people in Europe that died during the bubonic plague (sometimes referred to as Black Death).
The researchers found that people who had what researchers call a “good variant” of a particular gene named ERAP2 had a higher chance of surviving or not getting infected by the Bubonic plague. One of their conclusions is that the Bubonic Plague is what they call “selective pressure”- a pandemic as horrible as the bubonic plague, wiping out entire populations, can fast track evolution, or as one researcher puts it: “An evolutionary process called selective pressure encourages the survival of favorable genes in a population and discourages unfavorable genes. If any living organism survives long enough to pass favorable genes to the next generation, the species benefits by avoiding potential extinction.”*
So far, so good, but the consequences of these evolutionary processes many generations later may look different.
Today, the ERAP2 gene is connected to a number of autoimmune disorders, Crohn’s Disease being directly mentioned in the Nature article. Here’s one of the PI’s of the study, Hendrik Poinar: “These genes are underbalancing selection – what provided tremendous protection during hundreds of years of plague epidemics has turned out to be autoimmune-related now. A hyperactive immune system may have been great in the past but in the environment today it might not be as helpful.”
I know, it’s “old” news, but I am incredibly fascinated by this study- in a way the body/evolution deals with trauma the same way we deal with psychological trauma: focus on the survival, and deal with everything else at another point in time. Or it’s a scientific version of a pact with the devil- you get your wish, but it will cost you, even if it is hundreds of years later. Congratulations to the many researchers involved in this incredible project!
* scientists don’t think covid-19 may have this effect on us.