The 2010 discovery that early humans and Neanderthals once encountered one another and had babies was a scientific bombshell that electrified the field of human origins.Now, geneticists at the University of Pennsylvania say they have a better understanding of the nature of those prehistoric hookups, suggesting the trysts were mostly between male Neanderthals and female humans.The intriguing finding, published Thursday in the journal Science, could help explain why the Neanderthal ancestry that is present in humans today is unevenly distributed across the genome. However, it’s far from clear why prehistoric pairings between our species, Homo sapiens, and Neanderthals — who went extinct around 40,000 years ago — largely followed this pattern.AdvertisementAdvertisement“This is a fascinating and provocative hypothesis,” said Joshua Akey, a professor at Princeton University’s Lewis-Sigler Institute for Integrative Genomics, who wasn’t involved in the research. “I find it extraordinary that we can use genome sequences to infer aspects of social dynamics and mating patterns that occurred tens to hundreds of thousands of years ago.”Researchers don’t know exactly how often Neanderthals and members of our species encountered one another but a study published in 2024 suggested the two groups exchanged DNA at multiple points over the past 250,000 years as they migrated around the world. Neanderthals and Homo sapiens are also known to have interbred with a third species: Denisovans.Most humans carry a small percentage of Neanderthal DNA, a genetic legacy from those sexual interactions. In certain cases, those genes can still influence human health. Neanderthal DNA has been found to affect circadian rhythms, immune system function and the way some people feel pain.Mysteriously, however, the human X chromosome today appears to be what geneticists call an “archaic desert,” meaning it has next to no Neander …
