Loss of Genetic Diversity May Have Contributed to Neanderthal Extinction

A new study published in PNAS suggests that a loss of genetic diversity, triggered by a major glaciation around 75,000 years ago, may have contributed to the extinction of Neanderthals. Researchers analyzed mitochondrial DNA from ten Neanderthals found at six sites across Belgium, France, Germany, and Serbia, comparing it with 49 previously sequenced individuals. They found that prior to 75,000 years ago, Neanderthals were genetically diverse and widespread across Europe. However, climate cooling caused population contraction, with only a group in southwestern France surviving. This bottleneck reduced genetic diversity dramatically, making Neanderthals more vulnerable to threats like the arrival of Homo sapiens and further climate changes around 45,000 years ago. The species disappeared roughly 40,000 years ago. Co-author Cosimo Posth of the University of Tübingen noted that while no single cause explains their extinction, the lack of genetic diversity likely predisposed them to fail. Another PNAS paper supports this, finding Neanderthals lived in small, isolated groups prone to inbreeding.