Late Neanderthals Were Genetically Diverse, Not Inbred
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- Alba Bossoms Mesa and colleagues at the Max Planck Institute for Evolutionary Anthropology sequenced DNA from 27 Neanderthal remains across seven sites in Belgium and two in France, dated 52,500 to about 40,000 years ago — producing the first high-quality Neanderthal genome from the region (a woman cannibalized roughly 45,000 years ago in Belgium's Goyet cave).
- The 27 remains represented at least 11 individual Neanderthals, and analysis found no evidence of increasing harmful genetic mutations or declining genetic diversity — in contrast to inbred Altai Neanderthals from Siberia, where close-relative mating was documented.
- These northwestern Neanderthals split from other late Neanderthal groups in Croatia and southern Russia around 54,000 years ago and formed a distinct, well-connected regional population rather than a small isolated remnant on the brink of disappearance.
- Modern humans entered Europe about 47,000 years ago, overlapping with this Neanderthal group for many generations — yet none of the 27 genomes carried DNA from Homo sapiens, contradicting the assumption that interbreeding occurred wherever the two species coexisted.
- Chris Stringer of London's Natural History Museum said the absence of Neanderthal-to-human gene flow in these samples supports his hypothesis that late Neanderthals were losing fertile individuals to Homo sapiens groups in a one-way process, potentially accelerating their extinction.
- Bossoms Mesa offered alternative explanations: interbreeding may have happened primarily elsewhere (such as the Levant), hybrid offspring may have been unviable, or hybrid children may have been raised only within human social groups.
- Bossoms Mesa also pushed back on the extinction framing entirely, noting that "they're not really disappearing if part of them still survives in our genome."
Why it matters: Before this study, only four high-quality Neanderthal genomes existed — three from Siberia — meaning all inferences about Neanderthal social structure rested on a single geographic outlier. The new finding that northwestern European Neanderthals retained robust genetic diversity until near-extinction shifts the extinction debate away from inbreeding toward ecological pressure, competition with Homo sapiens, and one-way fertility loss to modern human groups, while the absence of interbreeding signals in this region forces researchers to reconsider where and how the two species actually mixed.
