The Black Death is an infectious disease caused by the bacterium Yersinia pestis. It may have killed up to half of Europe’s population.
Two years ago, researchers suggested that the plague might have left marks in human DNA. But recent studies disagree with these findings. Other studies highlight possible flaws in the methods used. More research is needed to finally resolve the debate about the plague’s impact on human DNA.
What Did Previous Research Suggest About the Plague’s Effect on Human DNA?
Scientists have struggled to recover DNA from ancient plague victims’ skeletons. The bone fragments are often small and contaminated with external materials. Much of the DNA might just be from soil and bacteria that entered the bones. But in 2022, a study claimed to find intact human DNA in these skeletons.
The researchers argued that the samples showed how humans evolved to adapt to disease. They claimed that these findings could influence today’s development of vaccines and drugs.
One clue was the ERAP2 gene. The study said this gene makes a protein that strengthens immunity against Y. pestis. It stated that people with ERAP2 were twice as likely to survive the plague.
The human leukocyte antigen (HLA) system was also believed to protect against Y. pestis. People with HLA gene differences were thought to be more immune to medieval diseases.
According to the 2022 study, genes that protect against the plague might worsen inflammation. ERAP2 was claimed to increase survival odds by 40% by boosting the immune response. However, the same mutation might also make inflammatory illnesses more likely.
What New Research Challenges Claims of Plague Alteration to DNA?
Recent research challenges the idea that Y. pestis altered the DNA of ancient humans. This study did identify significant changes in genome sequences over time. However, no specific genetic variation was pinpointed between pre- and post-plague samples.
The study shows that genetic diversity did not decrease after the Black Death. If people without certain gene variants were likely to die, diversity would reduce.
This recent research also could not confirm the link between HLA and surviving Y. pestis. However, the study acknowledges that more possibilities could be explored. Factors in the immune response to Y. pestis might not have been discovered yet. Further investigation is needed to settle this debate.
Another study criticized the 2022 findings. Randomization suggested that the gene changes over time might have been coincidental. Also, none of the four genetic traits believed to have mutated held up under scrutiny. Finally, they could not replicate the ERAP2 gene’s effect on people with Y. pestis.
Conclusion
The initial findings that linked human DNA evolution to plague survival were exciting. They offered new medical paths and seemed to shed light on ancient mysteries.
But recent studies question these earlier claims. Future research could clarify the relationship between human DNA and disease immunity.
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Logan Hamilton is a freelance writer for hire. He’s passionate about crafting crystal-clear, captivating, and credible content that elevates brands and establishes trust. When not writing, Logan can be found hiking, sticking his nose in bizarre books, or playing drums in a local rock band. Find him at loganjameshamilton.com.
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