Ancient DNA Provides 'Quantum Leap' in Understanding of MS

Around 5,000 years ago, a people called the Yamnaya swept into northwestern Europe on horseback, bringing their wagons, cattle, and sheep—along with genes that researchers believe are responsible for higher rates of multiple sclerosis in the region today. In a study published in the journal Nature, researchers say they found the link to a higher risk of the autoimmune disease after comparing hundreds of samples of ancient DNA from teeth and bones to data on 410,000 people identified as "white British" in the UK Biobank. The researchers believe that genetic variants that protected the Yamnaya against diseases carried by sheep and cattle ended up raising the risk of MS as sanitary conditions improved over time, making the variants "surplus to our immunological requirements," reports Reuters.

"We are a product of the evolution that happened in past environments, and in many ways we are not optimally adapted to the environment we have created for ourselves today," says study co-author Rasmus Nielsen, a population geneticist at the University of California-Berkeley. The researchers say their findings are a "quantum leap" in understanding the disease, which is twice as common in Northern Europe than Southern Europe, the BBC reports. "MS is not caused by mutations—it's driven by normal genes to protect us against pathogens," says study co-author Lars Fugger, an MS doctor in Oxford, England. Another co-author, University of Cambridge geneticist William Barrie, says the findings suggest recalibrating the immune system, instead of suppressing it, could help treat the disease.

The Yamnaya, who replaced the farmers who'd replaced hunter-gatherers thousands of years earlier, moved to Northern Europe from the steppes of what's now Russia, Ukraine, and Kazakhstan. "The Yamnaya were Europe's first true nomads," Barrie says, per Reuters. "They used domesticated cattle and horses to access the interiors of the Asian Steppe, where there is little to eat or drink, so carried everything with them on wagons. Physically they were unusually large, which we can see by measuring the skeletons and also genetically, and apparently fairly violent." The researchers say the highest rates of Yamnaya ancestry are found in Finland, Norway, Sweden, Iceland, and Ireland. (More multiple sclerosis stories.)