Evrim Yazgin
Cosmos science journalist
DNA from samples spanning 8,500–1,300 years ago shows how ancient Europeans adapted to the development of early agriculture.
Genes underwent significant changes in 14 regions of the genome.
For example, those associated with traits that help in the production vitamin D and digest milk into adulthood showed strong signs of selection, but only in the most recent time periods. This includes lighter skin pigmentation for vitamin D production in less sunny climates, and the ability to use milk as a nutritional source.
“It’s possible this ability to digest dairy was important to survival during periods of crop failure, food scarcity and disease,” says lead researcher Vagheesh Narasimhan from the University of Texas (UT) at Austin.
Immune-related genes underwent changes in different time periods, probably when ancient populations adapted to new diseases introduced by the spread of agriculture and migrations.
About half of the adaptive signals were detectable only in the oldest time periods. This suggests they later vanished due to genetic drift or were masked by population mixing.
More than 700 samples were taken from across Europe from modern-day Portugal and Britan in the west to Russia in the East. Samples were obtained from Scandinavia and the Mediterranean and everywhere in between.
Samples were grouped into 4 time periods: Neolithic, Bronze Age, Iron Age, and Historical.
The oldest samples come from the Neolithic Period (also known as the Late Stone Age) which ended about 3,700 years ago. This period of human development is marked by the beginning of settled lifestyles. Communities in the Neolithic were the first to learn to cultivate plants and domesticate animals for food. This represented a shift away from the hunter-gatherer lifestyle that had dominated for the previous 300,000 years of modern human existence.
“Studying ancient DNA lets us reach back in time, tracking evolutionary changes directly in historical populations,” says Narasimhan. “We’re revealing genetic signatures that have been largely erased or masked in present-day genomes.”
Even in a brief 7,000-year window, the DNA analysis was able to show evolutionary processes in these ancient European populations which are otherwise undetectable in modern genetic samples.
The team used a new statistical approach to examine the DNA data. This allowed them to scan for signs of natural selection.
“Our method provides a clearer picture of how and when certain traits were selected for, especially when those signals have been lost in modern genomes,” explains co-first author and UT Austin graduate student Devansh Pandey.
The analysis showed adaptations took place during the transition to farming as humans lived in closer proximity to each other and domesticated animals.
The ancient DNA analysis is published in Nature Communications.
