Ancient European migration patterns linked to modern-day disease risks
Study harnesses millennia-old human DNA to plot ‘genetic divide’ on origin and spread of health risks
Ancient migration patterns reveal why some Europeans are more at risk than others from a range of diseases including multiple sclerosis and Alzheimer’s, according to groundbreaking genomic research.
Millennia-old movements of hunter-gatherers, farmers and steppe pastoralists help explain the modern-day “genetic divide” in aspects such as height and susceptibility to diseases such as diabetes, say four papers published in Nature on Wednesday.
The pan-continental study offers a surprising account of how some prominent public health scourges have evolved — and possible clues on how to manage these risks in the modern era.
“This project has changed my view of both myself . . . and the history of Europe,” said Eske Willerslev, a professor at Copenhagen and Cambridge universities and one of the study’s authors. “What these papers are doing is setting the framework for how you use these ancient human genomes to understand the origin and spread of disease risk.”
Willerslev and colleagues sequenced genetic data from 317 radiocarbon-dated ancient skeletons and added this to existing information from 1,300 more specimens. The samples dated back as far as about 15,000 years and covered social transitions through the ages of hunter-gathering, farming and pastoralism.
A crucial turning point was the arrival of neolithic farmers from the Middle East in western Europe about 11,000 years ago, the researchers discovered. This created a “genomic boundary” on the continent that ran from the Black Sea to the Baltic and lasted for thousands of years, with enduring consequences for public health and disease prevalence.
“Archaeologists have been talking about this divide for a long time,” said Morten Erik Allentoft, professor in evolutionary genomics and biodiversity at Copenhagen university, who was involved in the research. “But witnessing this in genetic data is one of the really cool things about this [study].”
The insights on multiple sclerosis came from comparing part of the ancient data with the genetic information of more than 410,000 present-day self-identified white Britons.
MS is a so-called autoimmune disease, in which the human body hurts itself through its defensive response to invading microbes, with damage to nerve cells in the brain and spinal cord that can cause serious disability. This disease, which affects more women than men, is most prevalent in Europe and in particular in the northern part.
Yamnaya pastoralists from the Pontic Steppe linking eastern Europe to central Asia brought genes associated with a heightened MS risk to Europe about 5,000 years ago, the researchers found. The Yamnaya’s higher concentration in northern Europe helps explain the greater prevalence of MS there.
The findings suggest a striking case of an ancient boon becoming a modern burden. The pastoralists’ genetic profile may have done them more good than harm, as it helped protect them against diseases carried by their herds.
“These variants were giving [ancient] people an advantage of some kind,” said William Barrie, co-author of the MS paper and a research associate at Cambridge university. “We think it was protecting them from their animals’ pathogens.”
Another strand of the research looked at how historical migration linked genetically to predisposition to various contemporary illnesses. Western hunter-gatherer ancestry — prominent in the Baltic states, Belarus, Poland and Russia — was more strongly linked to traits related to Alzheimer’s, high cholesterol levels, blood pressure and diabetes.
By contrast, neolithic farmer lineage, more prominent in southern Europe, was connected to a greater disposition to anxiety, guilty feelings and irritability.
The scientists further found that Steppe antecedents appeared to play a part in why modern northern Europeans are taller on average than southern counterparts. This ancestry peaks in Ireland, Iceland, Norway and Sweden.
The study shows how “shifts in culture and lifestyle” of ancient human populations “have had long-term effects and are still affecting us today”, said Selina Brace, principal researcher in ancient DNA at the Natural History Museum.
“Anything that moves in the direction of a greater understanding of these diseases holds potential to help treat them,” said Brace, who was not part of the research.
The researchers’ discoveries about disease risks in white Europeans highlight the potential to apply the approach more widely both within and beyond the continent.
The techniques should be used to deepen understanding of how vulnerability to illnesses has evolved in populations around the world, argued Samira Asgari, assistant professor at New York’s Icahn School of Medicine at Mount Sinai, and Lionel Pousaz, a science writer.
“It is crucial to extend these studies to diverse human populations to better understand how differences in population history might have contributed to the risk of autoimmune diseases such as multiple sclerosis,” according to a commentary also published in Nature by the two authors, who were not involved in the European research.
“Although human biology is shared, each population has a unique history and focusing on a single population limits opportunities for discoveries that can bring insights that advance medicine.”