Ancient DNA shows what really spread the farming revolution

Farming spread across prehistoric Europe mostly because farming communities moved, not because local hunter-gatherers copied their ways. Cultural adoption played only a minimal role in the Neolithic transition, the period when agriculture took hold.

A team of researchers at Penn State combined ancient DNA, archaeology, and computer simulations to separate the effects of migration from the uptake of new practices.

The team modeled population movements, growth, and learning, then tested those models against genetic ancestry from hundreds of Neolithic individuals and against the known pace of farming’s advance from the Middle East into Europe.

Two sciences unlock farming’s spread

Christian Huber, an assistant professor of biology at Penn State and senior author on the paper, noted that archaeology and genetics offer complementary windows into this transition.

“Artifacts and isotopes in ancient bones can reveal whether a person relied on domesticated plants or animals, reflecting the adoption of new farming practices,” said Huber.

“At the same time, DNA preserved in those bones can show where people’s ancestors came from, providing evidence of migration, or the movement of farming populations into new regions.”

Archaeological traces show when domesticated crops and animals appeared. Genomes preserve who arrived with them.

By fusing those records within a single statistical framework, the team could estimate how much of farming’s spread came from people on the move and how much from ideas crossing cultural lines.

Migration versus culture finally measured

“This has been a long-standing question – and disentangling the roles of migration and cultural adoption has been a goal of archaeologists and anthropologists for decades,” said study lead author Troy LaPolice, a doctoral student at Penn State.

“What we found was surprising: when cultures spread through migration, it is not guaranteed local ancestry patterns will change, but the spread of farming managed to leave a strong and lasting impact on European ancestry.”

The researchers simulated the front of farming as it rolled out from the Fertile Crescent roughly 10,000 years ago, reaching into the Balkans, then north and west across the continent. They fit those simulations to radiocarbon timelines and to ancestry profiles from 618 ancient individuals.

The results allowed them to assign weight to two forces – movement of farming groups and adoption by foragers – and to test which combination best reproduced the record.

Farmers moved, ideas spread slowly

The answer was clear. Migration dominated. Cultural transmission, the flow of practices without the movement of people, barely nudged the pace.

The team’s estimates put the “cultural effect” at about half a percent. Hunter-gatherers in most places continued to forage even as farmsteads appeared nearby and, over generations, replaced their way of life.

“The assimilation rate, the rate at which hunter-gatherers were grafted into farming communities, was actually very low  –  only about one in 1,000 farmers converted a hunter-gatherer to farming each year,” Huber said.

“As a result, cultural transmission had almost no effect on how quickly farming spread. Still, even at this low rate, it left a lasting mark on the DNA of Europeans today and introduced useful genetic traits into the growing farming communities.”

That small but steady flow mattered biologically, even if it mattered little to the speed of the transition.

Genes from local foragers entered the expanding farming populations. Some of those variants likely helped the newcomers adapt to new environments as they moved north into different climates and daylight regimes.

Farming and foragers rarely mixed

The models also point to strong social boundaries. According to the team’s analysis, farmers overwhelmingly mated with farmers, and foragers with foragers. “Between-group” pairings were rare, on the order of less than three percent.

That pattern aligns with other ancient DNA studies showing persistent genetic differences between neighboring groups that shared landscapes for centuries.

Those findings help explain why the genetic imprint of the first farmers is so pervasive in Europe today. Once agricultural communities established themselves, their numbers grew more quickly than those of foragers.

Even with little intermarriage or conversion, demographic momentum carried their ancestry far.

DNA helps rewrite early history

“It’s really interesting to be able to understand a time period before any written or oral history,” LaPolice said. “This intense interdisciplinary project allowed us to undertake a new kind of historical reconstruction.”

The approach tested not just a story but a set of mechanisms. It allowed the team to ask what combinations of movement, growth, and learning could produce the archaeological and genetic patterns we see.

It also let them probe how sensitive their conclusions were to assumptions about mating, mobility, and population size.

Method offers tools for archaeology

The study adds to a growing body of work showing how ancient genomes can clarify human prehistory when paired with robust models.

It also echoes the team’s recent methodological papers assessing common ancestry tools – useful when applied carefully, but misleading when pushed beyond their limits.

“This research highlights the power of combining genetic data with archaeological models to uncover the complex behavioral mechanisms of our past,” Williams said. “Looking forward, I see this paving the way for a reevaluation of other major prehistoric cultural shifts.”

From metalworking to herding, from language dispersals to the rise of cities, many transformations reshaped ancient lives. The Penn State team’s framework offers a way to test whether those farming changes spread through people, ideas, or – most often – some blend of both.

The study is published in the journal Nature Communications.

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