DNA extracted from the bones and teeth of ancient Europeans who lived up to 34,000 years ago is providing valuable information about the origins of multiple sclerosis, an often disabling neurological disease, and has shown that genetic variants that now increase the risk of multiple sclerosis, one once served to protect people from diseases transmitted by animals, informs Reuters.

The findings come from a study that involved sequencing ancient DNA taken from 1,664 human skeletons from various locations in Western Europe and Asia. These ancient genomes were then compared to modern DNA stored in the UK Biobank, which contains around 410,000 samples from people who identify as “white British” and more than 24,000 other people born outside the UK, to distinguish changes over time .

One startling discovery was related to multiple sclerosis, a chronic disease of the brain and spinal cord believed to be an autoimmune disease that causes the body to mistakenly attack itself.

The researchers identified a major migration event about 5,000 years ago, at the beginning of the Bronze Age, when herders, known as Yamnaya, moved into Western Europe from an area that includes modern-day Ukraine and southern Russia.

They carried genetic traits that were useful at the time and provided protection against infections that could occur in their sheep and cattle. As sanitation improved over the millennia, the same choices increased the risk of developing multiple sclerosis. This helps explain, the researchers say, why Europeans in the north of the continent have the highest prevalence of the disease in the world, twice that of southern Europe.

“We are the product of evolution in past environments, and in many ways we are not optimally adapted to the environment we have created for ourselves today,” said Rasmus Nielsen, a population genetics researcher at the University of California, Berkeley. one of the coordinators of the study published on Wednesday in the journal Nature.

About 11,000 years ago, farmers from what is now Turkey moved to Western Europe, replacing hunter-gatherers. These farmers were those who were later replaced by the population of Yamnaya.

“Yamni were the first true nomads in Europe. They used domesticated cattle and horses to access the interior of the Asian steppe, where food and water were scarce, so they carried everything with them in wagons. Physically they were extremely large, which we can see by measuring the skeletons, but also genetically, and apparently quite violent,” said William Barry, a geneticist at the University of Cambridge and a co-author of the study.

“We believe that much of the replacement that took place was caused by the war,” Rasmus Nielsen added.

Europeans from the north of Europe show a high degree of ancestry associated with the Yamnai population, with a maximum in Ireland, Iceland, Norway and Sweden, and this degree gradually decreases towards the south of the continent.

The results highlight how genetic traits can turn from beneficial to harmful as conditions evolve.

“Pathogenic infections increased in the Bronze Age due to the close proximity of humans and domestic animals, as well as increased population density,” said Evan Irving-Pease, an expert in computational evolutionary biology at the University of Copenhagen and co-author of the study.

“Only in the modern era, with widespread hygiene and medical care, have these genetic variants become redundant for our immunological needs, leading to an increased risk of developing multiple sclerosis and other autoimmune diseases,” he said, Evan Irving added. Pea.

The results of the new study may have implications for the research and treatment of multiple sclerosis.

“This is changing our understanding of multiple sclerosis by helping us understand its origins. We can think of multiple sclerosis as the result of an immune system that evolved to effectively fight off a range of infections in the human past, but now exists in a very different environment. “This difference between the past and present sanitary environment probably causes the immune system to be overactive. This means that we should be trying to calibrate the immune system, not suppress it,” said William Barry.

Why are northern Europeans taller than southern ones

A new study highlighted other characteristics of Europeans.

Because the Yamnai were genetically predisposed to be tall, modern northern Europeans tend to be taller than southern Europeans, who have more ancestry from Neolithic farmers who were genetically predisposed to short stature.

Researchers have found that Eastern Europeans have an increased genetic risk of Alzheimer’s disease and type 2 diabetes. Scientists also found that lactose tolerance, the human body’s ability to digest the sugar in milk and other dairy products, appeared in Europe about 6,000 years ago. (Agerpress)