The Black Death has been described as the largest deadly event in recorded history, killing 50% of Europe’s population in less than five years.
A recent study found evidence that the darkest periods in recorded human history changed the frequency of certain immune-related genetic mutations and affected our susceptibility to disease today. According to findings published in Nature, scientists from the University of Chicago, McMaster University and the Pasteur Institute have revealed that the genes that protected people from the Black Death 700 years ago increase the risk of having of Crohn’s disease and rheumatoid arthritis.
Scientists studied DNA from the teeth and bones of people who died before, during, and after the devastating bubonic plague that ravaged Europe, Asia, and Africa from 1346 to 1353.
Their results found that a genetic variant called ERAP2 was protective in the Middle Ages when people were protected against the plague.
Today, however, it is associated with a higher susceptibility to autoimmune diseases – a “balancing” effect that evolution has on our genome.
“This is the first evidence, to my knowledge, that the Black Death was a truly significant selective pressure for the evolution of the human immune system,” said study author Luis Barreiro of the University of Chicago.
And there are many theories about human evolution and how pathogens arose, so formally clarifying which pathways and genes are targeted really helps us understand what allows humans to adapt and exist today.
Affecting Europe, Western Asia, and North Africa, the Black Death was the most famous epidemic in history.
Historians estimate that the global bubonic plague killed between 30 and 60% of people in cities in North Africa, Europe, and Asia, with a major impact on humanity and apparently on our genome.
Early DNA research identified a bacterium called Yersinia pestis as the cause of the Black Death.
Europeans at the time of the Black Plague were very vulnerable to begin with, as they had not been exposed to Yersinia pestis recently.
In this study, the team focused on a 100-year window before, during and after the Black Death, which is said to have arrived in London in the fall of 1348.
More than 500 ancient DNA samples were taken and analyzed from the remains of individuals who died, died or survived before the plague.
The bones were taken from about 200 remains from London and Denmark. The research team focused on a gene called ERAP2, which has a particularly strong link to allergies.
The scientists discovered that those with two copies of a particular genetic variant, called rs2549794, made full-length copies of ERAP2, and therefore more of the functional protein, compared to another variant that resulted in in a truncated, non-working copy. . a replica.
Having both copies of functional ERAP2 allows the production of functional proteins, which are molecules involved in helping the immune system recognize the presence of infection.
According to the scientists, these transcripts allowed “better neutralization of Y. pestis by immune cells.”
Those with two identical copies of the “good” ERAP2 gene survived the plague at a higher rate than those with one set of copies of the malfunctioning variant, the scientists said.
Possession of this variant would make a person 40% more likely to survive the Black Death than those without it.
This also means that survivors of the Black Death passed on this “good” ERAP2 gene variant to their children, helping them survive subsequent waves of the pandemic.
However, while the genetic variant was protective against plague in the Middle Ages, today it is associated with increased susceptibility to autoimmune diseases – part of evolution’s balancing act in our genome.
Hendrik Poinar, Professor of Anthropology at McMaster University and co-author of the study, said: “Diseases and epidemics like the Black Death leave traces in our genomes for archeology projects to discover these. This is the first look at how epidemics arise. We can change our genomes invisibly in modern societies.” “These genes have been subject to a balancing selection that provided enormous protection during centuries of plague epidemics and now appear to be associated with autoimmunity. An overactive immune system may have been a good system in the past, but may not be beneficial in today’s environment.”
Source: Daily Mail
Source: Arabic RT
