Genetics

This research article demonstrates that the contemporary prevalence of multiple sclerosis (MS) in Northern Europe is primarily a consequence of a massive migration of steppe pastoralists into the continent approximately 5,000 years ago. By analyzing a vast dataset of 1,750 ancient genomes alongside modern biobank data, the authors identified that MS-associated risk variants—most notably the HLA-DRB1*15:01 allele—emerged in the Pontic-Caspian steppe and underwent positive selection. This selection was likely a pleiotropic byproduct of an adaptive immune response, where variants that once conferred survival advantages against zoonotic pathogens and infectious diseases in a pastoralist environment now predispose modern populations to autoimmune neuro-inflammation. The study ultimately concludes that the dramatic lifestyle shifts of the Bronze Age, including increased population density and animal domestication, fundamentally reshaped the European immunogenetic landscape, creating a historical "mismatch" that continues to influence disease susceptibility in the present day.