Unearthing the Past: How a Genetic Crisis Led to Neanderthal Extinction 100,000 Years Ago

The Neanderthals went extinct, and we’re still trying to understand why. Some researchers think that changes in the climate, competition with modern humans, or even conflicts contributed to their end. A new study suggests that a significant drop in genetic diversity may have played a big role in their extinction.

This research was conducted by an international team who looked into the anatomy of Neanderthals’ ear canals. By examining their ear structures and comparing them to existing Neanderthal DNA, the team found clear signs of a genetic bottleneck over 100,000 years ago.

The team compared the ear canal shapes in Neanderthal fossils from various sites in Europe and western Asia with those of modern humans. This comparison helped determine how diverse different human groups were at that time.

One key site for this study was the Krapina fossil site in Croatia, which dates back about 130,000 years. Other important sites included late Neanderthal locations in France, Belgium, and Israel, dating from 41,000 to 64,000 years ago. The findings suggest that between these two timeframes, there was a decline in genetic variation among Neanderthals, indicating a shrinking population before they vanished.

The researchers noted this decline pointed to major changes in the Neanderthal population prior to their extinction around 40,000 years ago. They didn’t specifically analyze why genetic diversity decreased but mentioned factors like climate changes or rising competition as possible reasons.

According to anthropologist Mercedes Conde-Valverde, the study painted a broad picture of Neanderthal evolution by including fossils from many different locations and time periods. They found that the drop in genetic diversity from the Krapina sample to later Neanderthals was especially striking, providing solid evidence of a bottleneck.

Interestingly, the fossils from Krapina exhibited a diversity level comparable to much older samples that are around 430,000 years old. This finding challenges the belief that significant genetic bottlenecks happened earlier in Neanderthal history, suggesting that the decline occurred closer to their extinction.

The researchers are excited to extend their ear structure analysis to other fossils worldwide. They hope this will deepen our understanding of how Neanderthals lived, traveled, and ultimately disappeared.

This study highlights a new way of estimating genetic diversity in Neanderthal populations. The full findings are available in Nature Communications.