According to a study published in the journal Nature earlier this week, the Black Death may have altered not just society but also the genome of survivors’ descendants!
Barreiro, the study’s author, points out that the mortality rate was more than 200 times higher than the one of COVID-19, just to put things into perspective.
It is believed that it likely wiped out between 30 and 50 percent of the people living in the United Kingdom and other parts of Europe at the time.
With that being said, Barreiro and his colleagues believe that the survivors were able to pass down a mutation still carried today.
While it helped protect them against the pathogen, it now comes with an increased risk of autoimmune diseases.
Barreiro explains that “The same genetic variant we find to be protective against Yersinia pestis is also associated with an increased risk for Crohn’s disease today.”
This paper shows how older pandemics may prepare the immune system to overcome other pandemics that are yet to come.
David Enard, an evolutionary biologist at University of Arizona shared that “The evolution is faster and stronger than anything we’ve seen before in the human genome. It’s really a big deal. It shows what’s possible [for humans], in terms of adaptation in response to many different pathogens.”
As part of the study, the scientists did something incredible – collected DNA from plague victims that passed away no less than 700 years ago!
This was only possible due to the fact that London officials used the East Smithfield cemetery solely during the Black Death pandemic, allowing the team to know the bodies’ age with precision.
They were also able to analyze DNA from people who died during 3 particular time periods – before the Black Death, during the pandemic and the time that came after it was all over.
The next step was to look into genes directly involved with the immune system to figure out whether or not there was a correlation with their survival.
And sure enough, genetic differences between those who died of the Black Death and those who survived were found – four of them!
These mutations are believed to have given them a significant advantage.
More precisely, one of them, known as ERAP2, gave people at the time a 40 percent survival advantage, which is the biggest evolutionary advantage recorded in humans, as per Enard.
The team of scientists found that those who carry this mutation are likely to kill invading pathogens quicker than people who don’t have it.
