Discoveries

November 10, 2022

The Red Crosses’ Splinters

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Between 1346 CE and 1353 CE, the bubonic plague known as The Black Death killed as many as 200 million people across Western Eurasia and North Africa.

Now, scientists have found after studying the genes of victims and survivors that the plague has impacted humans today, Sky News reported: It has influenced the evolution of the human immune system and opened the door to other diseases common today such as rheumatoid arthritis.

For their study, researchers collected more than 500 DNA samples from victims and survivors buried in three cemeteries in London, the UK. The individuals lived between 1000 and 1500 CE, according to the New York Times.

The team searched for signs of genetic adaptation related to the plague and found four genes that were responsible for producing proteins to better protect against invading pathogens. The plague was caused by the bacterium Yersinia pestis.

Specifically, they discovered that people who had two identical copies of the ERAP2 genes were nearly 50 percent more likely to survive than those who didn’t.

Study author Luis Barreiro explained that the Black Death was so impactful that it was “an important selective pressure to the evolution of the human immune system.”

But that boosted immunity came with a price: Individuals with the protective genes are more susceptible to immune disorders, such as Crohn’s disease.

Still, Barreiro and his colleagues plan to further analyze the genes, believing that they are important in the fight against diseases.

“It was important in the past, and it most likely is going to be important today,” he told the Times.

This story originally appeared in the November 10, 2022 newsletter, Remaking the Wall.