Stone Age hunter-gatherers fathered children with European farmers
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Descendants of Stone Age farmers who settled in Europe inherited an unusually high proportion of immune genes from local hunter-gatherers, the only reason early humans became more resistant to pathogens. suggests that it was not just the development of agriculture.
It has long been thought that ancient farmers had better immune systems than hunter-gatherers because they lived in more densely populated environments, were in closer proximity to animals, and had increased exposure to pathogens. . As these farming populations expand, their immune genes are best adapted and will be passed on to their offspring.
But the story is more complicated than that. “Those early farming groups expanded into Europe, bringing with them lifestyles and technology, [were] They are also European hunter-gatherers,” said Pontus Skoglund of the Francis Crick Institute in London, and the two groups were intermingled.
To learn more, Skoglund and his colleagues analyzed the genomes of 677 ancient individuals from across western Eurasia, spanning about 12,000 to 5,000 years ago.
The team divided the genomes into three groups. Early farmers, European hunter-gatherers, and later individuals of mixed genetics who migrated westward from the territories now occupied by Turkey and the Balkans. “Fast forward a few thousand years and the remaining agricultural groups now have about 20% of their ancestry traced back to hunter-gatherers,” he says Skoglund.
However, in a specific genomic region called the major histocompatibility complex (MHC), the split was closer to 50:50. The MHC contains many genes for adaptive immunity that target the body to specific pathogens, but it’s unclear exactly why the hunter-gatherer genes were selected, Skoglund said. increase.
The simplest explanation is that hunter-gatherers may have been better adapted to Western European pathogens, so that once farmers settled in Western Europe, their genes might have taken an advantage.
However, thanks to evolutionary eccentricities that mean groups that typically inherit a small number of genes, such as hunter-gatherers, can provide more genes for functions whose diversity is important, such as immunity, alternatives have emerged. there is. The offspring will be able to survive various diseases.
MHC plays a big role in determining whether we can survive certain infections, says Mark Thomas of University College London, who was not involved in the study. “So, from an evolutionary perspective, it makes sense that we are very diverse for the MHC, which means we can fight off more pathogens,” he says.
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