Ancient DNA taken from the bones and teeth of people who lived in Europe 34,000 years ago is giving us important information about the beginnings of multiple sclerosis (MS), a brain and spinal cord disease. Scientists discovered that certain genetic traits, which now make people more likely to get MS, used to protect against diseases transmitted by animals. They studied the DNA of 1,664 ancient individuals in Western Europe and Asia, comparing it to the DNA of over 410,000 modern people in the UK Biobank.

One major finding highlighted a crucial migration event around 5,000 years ago during the Bronze Age. The Yamnaya people, nomadic herders from present-day Ukraine and southern Russia, brought genetic traits that were helpful back then, protecting against infections from their livestock. However, as hygiene improved over time, these same genetic traits increased the risk of MS, especially in Northern Europeans. This explains why MS is more common in Northern Europe. The study shows that genetic traits, once helpful, can become harmful as conditions change. It suggests that MS, viewed as an autoimmune disorder, may stem from the immune system adapting to historical challenges. It also reveals insights into European traits, like height differences influenced by ancient genetics, challenging common MS ideas. Emphasizing the need to adjust, not suppress, the immune system in treatment, this has wider implications for understanding and addressing MS, considering environmental impacts on genetic traits.