Uncovering Genetic Diversity: Surprising Insights into the Last Neanderthals

Recent findings indicate that the last surviving Neanderthals in northwestern Europe lived in genetically diverse and tightly-knit groups. This challenges the long-held belief that inbreeding was the primary driver behind their extinction approximately 40,000 years ago.

Despite the limitations in studying Neanderthal genetics (Homo neanderthalensis), due to the scarcity of well-preserved specimens, recent genomic analyses highlight that these ancient humans experienced periods of decreased diversity. However, the latest data suggests that inbreeding was not the foremost factor contributing to their decline.

Research led by Alba Bossams Mesa and his team at the Max Planck Institute for Evolutionary Anthropology, Leipzig, sequenced DNA from 27 Neanderthal remains sourced from diverse locations in Belgium and France, dating back as far as 52,500 to 40,000 years ago. Significantly, one genome revealed that a woman from Belgium’s Goyet Cave was cannibalized around 45,000 years ago.

“These newly analyzed genomes are crucial as they represent some of the youngest known Neanderthals, offering new perspectives on their genetic diversity during their extinction period,” explained Chris Stringer from the Natural History Museum, London.

Bossoms Mesa and his colleagues established that these 27 specimens belonged to at least 11 distinct Neanderthals. While overall diversity in Neanderthals was lower than that of modern humans, this group showed no substantial increase in detrimental genetic mutations or significant decreases in diversity.

In contrast to other Neanderthal populations, such as those in the Altai region of Siberia, which displayed evidence of inbreeding, Bossams-Mesa pointed out that these northwestern Neanderthals were closer to extinction yet displayed greater genetic diversity than their eastern counterparts.

The genetic findings also revealed that these Neanderthals were more closely related to each other than to late Neanderthal groups found further east in Croatia and southern Russia, splitting from a common ancestor approximately 54,000 years ago.

The broader implication suggests that the Altai Neanderthals may not accurately represent the entire species. Instead, the neanderthals from northwestern Europe belonged to a broader, interconnected population rather than a mere isolated group, says Bossams-Mesa. Different regional populations likely experienced varied life histories amid significant ecological and demographic shifts.

Modern humans made their entrance into Europe around 47,000 years ago, coexisting with this Neanderthal population for multiple generations. However, genomic evidence from these European Neanderthals reveals no interbreeding with modern humans, despite widespread indications of hybrids found elsewhere.

“This discrepancy raises intriguing questions about the interactions and power dynamics between Neanderthals and modern humans, which remain poorly understood,” noted Tarshika Vimala from UC Berkeley.

Bossoms Mesa posits various scenarios for this finding. Among them is the possibility that interbreeding predominantly occurred in different regions, such as the Levant, or that social dynamics or incompatibility with hybrids might have led to their nurturing primarily within human communities.

Stringer contemplates that the patterns of genetic exchanges into modern human populations reinforce the notion that late Neanderthals were losing reproductive capabilities, contributing to their eventual decline.

Perhaps it’s essential to rethink their status. “Even if remnants of their DNA exist in our genomes, Neanderthals haven’t truly vanished,” asserts Bossoms-Mesa.