Farming was thought to have originated and spread culturally from a single population in what is now the Middle East, but it has changed our world for both better and worse.
The ancient genomes suggest that farming was more complicated than a simple spread and adoption of a new culture.
The genomes of 15 humans who lived between 10,000 and 7,000 years ago, along with 10 previous humans, show a complex picture of population expansion, contraction, and migrations in the lead up to this massive human transformation.
The ancient DNA from skeletons from the oldest cemeteries of Central Europe and the earliest farming villages in the Aegean basin was used to sequence each individual.
The University of Bern population geneticist said that they get more detail about the demographic history of those populations.
The researchers could model even further back using this data. When the last ice age was at its most severe around 23,000 years ago, hunter-gatherers from Europe to the Fertile Crescent region had large populations that spread across the vast geographical expanse.
The group was rendered into three isolated populations because of the pressure and scarcity that came with the cold climate. The European hunter-gatherers had a big drop in genetic diversity.
The locations of some of the key sites. Marchi et al., Cell, 2022.
It was previously thought that small population sizes were the reason for low genetic diversity in hunter-gatherers.
The environment forced them to retreat into the milder regions and now it looks like they were much more connected.
The team believes the population may have dropped to less than 400 individuals, which is supported by archeological evidence.
The middle group centered around the Aegean region and the eastern group around the Fertile Crescent intermixing were separated and fragmented by the cold Older Dryas period 13,800 years ago.
It was from this group in central Anatolia that some of the early farmers arose around 12,900 years ago, following another connection with the European hunter-gatherers. They became the ancestors of many people in Europe today.
The populations around Southwest Asia and Europe were in the lead up to farming. Marchi et al., Cell, 2022.
The team wrote in their paper that strong genetic drift during their expansion through Anatolia made western early farmers look more similar than they actually were.
The model provides a time frame for the differentiation of the major groups in Southwest Asia and Europe from the last maximum until the introduction of agriculture.
The findings support the theory that after an initial spread of farming in the Fertile Crescent through cultural adaptation, farming spread from this region through to the Aegean Basin and beyond.
Marchi and the team explain that we need high-quality genomes from the Fertile Crescent and central Anatolia to confirm the scenarios and fill in some of the remaining gaps.
Cell published this research.