- The Black Death which ravaged Europe 670 years ago may still be harming humans today a study found.
- Genetic mutations that helped humans survive the plague increased the risk of chronic diseases, it said.
- The study suggests outbreaks can shape human health long after they have died out.
The infamous Black Death plague, which ravaged Europe 670 years ago, is still influencing human health today, a pioneering study found.
The study, published in the peer-reviewed journal Nature on Wednesday, found that people who survived the bubonic plague of the mid-1300s were much more likely to carry a certain mutation.
But the mutation has a downside, the study said: increased risk of chronic and potentially debilitating conditions like Crohn’s disease and rheumatoid arthritis.
“This suggests that populations that survived the Black Death paid a price, which is to have an immune system that increases our susceptibility to react against ourselves,” said study author Luis Barreiro, a professor of genetic medicine at the University of Chicago, in an email exchange with CNN.
A tradeoff that haunts us hundreds of years later
“It’s a very cool study,” James Lee, who leads the genetic mechanisms of disease lab at the Francis Crick Institute in London, told Insider.
“We’ve known that many of the regions of our DNA contribute to the development of these sorts of diseases. The question has been: why do we have these regions?” said Lee, who was not involved in the study.
Scientists have suspected for some time that outbreaks may shape the genetic makeup of humans, but it’s been very difficult to prove.
The Black Death, one of the greater killers in human history, was the perfect model to look at, Lee said.
In just five years between 1346 and 1350, the Black Death, a pandemic caused by the bacteria Yersinia Pestis, killed tens to hundreds of millions of people, many before they were old enough to have children.
By looking at the genome of 206 human remains buried in mass graves in the UK and Denmark before, during, and after the Black Death, scientists measured four mutations, called genetic variants, which changed in prevalance after the outbreak, suggesting they either helped or hindered people’s ability to survive.
One of the variants, with the complicated name of rs2549794, drew particular attention because it has been unequivocally linked to the development of Crohn’s disease — an autoimmune condition that causes inflammation of the gut.
“It’s huge, we see a 10% shift over two to three generations, it’s the strongest selection event in humans to date,” study author Professor Hendrik Poinar, an evolutionary geneticist from McMaster University, told the BBC.
“It’s the first study to show that some of the tiny changes in our DNA that we now know contribute to the development of diseases like Crohn’s disease actually arose and became more frequent specifically due to one event in history,” Lee said.
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