Lactose Intolerance Has Been In European Genetics For Thousands Of Years

Top view of the Dolmen of Oberbipp, one of the largest burial sites analyzed in the study. Urs Dardel, Archäologischer Dienst des Kanton Bern

Ancient cattle and sheep farmers from modern-day Ukraine gradually mixed with Europeans as far back as 2800 BCE, and among them was the oldest known Europeans to have genetic characteristics of lactose intolerance.

Genetic analysis and radiocarbon dating of nearly 100 ancient skeletal remains from Neolithic settlements in Switzerland is lending insight into the continent’s earliest inhabitants, both illuminating where they came from and how they lived, according to a new study published in Nature Communications.

Switzerland’s rich archaeological record makes it a prime location to study the origins of Europeans. Neolithic settlements are found throughout Central Europe, from lakeshores and bogs to Alpine valleys and high mountain spaces. Previous studies have shown that during the Neolithic period, around the time when civilizations started to rise about 12,000 years ago, drastic changes occurred as sheep and cattle farmers arrived from the Pontic-Caspian steppe in modern Ukraine. At this time, an emergence of Corded Ware Complex (CWC) cultural groups began, groups believed to be the common ancestor of Celtic, Germanic, Baltic, and Slavic groups. But exactly when these migrants arrived in Central Europe and how they mixed with the residents at the time has largely remained a mystery.

To begin to piece the ancient puzzle together, a team of researchers from the University of Tübingen, the University of Bern, and the Max Planck Institute for the Science of Human History radiocarbon-dated bones from 96 ancient skeletons across 13 Neolithic and Bronze Age sites in Switzerland, southern Germany, and the Alsace region of France. Mitochondrial genomes were completely reconstructed and compared against nearly 400 genomic information held within a databank.

Layer of the human remains found in situ in the Dolmen of Oberbipp in Switzerland. Archäologischer Dienst des Kanton Bern (Switzerland), Marianne Ramstein

The researchers found that the new group arrived as early as 2800 BCE but their genetic dispersal was complex and gradual. By and large, social and family structures remained biologically the same before and after people arrived from the Pontic-Caspian steppe, suggesting that the different societies did not intermix.

"Remarkably, we identified several female individuals without any detectable steppe-related ancestry up to 1,000 years after this ancestry arrives in the region," said lead author Anja Furtwängler of the University of Tübingen's Institute for Archaeological Sciences, in a statement.

Further genetic testing and analysis of stable isotopes determined that many societies were patrilocal, meaning that the men stayed where they were born and women came from distant families yet still did not have steppe ancestry.

"Since the parents of the mobile females in our study couldn't have had steppe-related ancestry either, it remains to be shown where in Central Europe such populations were present, possibly in the Alpine mountain valleys that were less connected to the lower lands," said Johannes Krause, director of the Department of Archaeogenetics at MPI-SHH and senior author of the study.

The study also presents one of the earliest evidence of adult lactose intolerance in Europe, dating back to around 2100 BCE, a genetic mutation that is of “high frequency” in Europe today but is largely absent in late and middle Neolithic samples. This suggests that lactose intolerance increased in frequency at the end of the Neolithic period and increased after the beginning of the Bronze Age.

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