Neandertals In North-Western Europe In Focus

New genetic study reveals regional diversity shortly before Neandertals disappeared

To the Point

• A new high-resolution view of late Neandertals: Researchers generated genetic data from 27 late Neandertals from Belgium and France, including a high-coverage genome from Goyet Cave dating to around 45,000 years ago.
• Regional connectivity: Most Neandertals from the Meuse Basin and nearby regions were more closely related to each other than to late Neandertals in other parts of Europe, pointing to strong regional connections.
• No recent modern human ancestry: Despite living at a time when early modern humans were already present in Europe, these Neandertals show no sign of recent mixture with them.
• No signs of progressive genetic decline: The genomes show no evidence of increasing genetic load or reduced diversity over time, providing little support for the hypothesis that genetic deterioration was the main cause of Neandertal extinction.

A new genetic study provides the most detailed picture to date of late Neandertal diversity in North-Western Europe. By analysing ancient DNA from remains found in Belgium and France, an international team led by researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig was able to reconstruct the genetic relationships of 27 Neandertals who lived shortly before Neandertals disappeared around 40,000 years ago.

The researchers analysed the genomes of Neandertals from ten archaeological sites, focusing particularly on the Meuse Basin in Belgium, an area with a high concentration of late Neandertal sites (i.e., those Neandertals who lived towards the end of Neandertal existence) . The dataset includes a new, high-coverage genome from an individual from Goyet Cave who lived around 45,000 years ago. “Until now, we only had four high-quality Neandertal genomes and a limited number of lower-quality ones, so most questions about the regional diversity of Neandertals have been difficult to address,” says first author Alba Bossoms Mesa, a doctoral researcher at the Max Planck Institute for Evolutionary Anthropology. “By generating genetic data from multiple individuals from the region of present-day Belgium and France, we can now examine late Neandertal populations in much greater detail.”

A connected but diverse population

Previous high-quality genomes had shown that some Neandertal groups, particularly those in the Altai region of Siberia, lived in small, genetically isolated communities, with evidence of mating among close-relatives. In contrast, in this new study the researchers found no evidence for recent mating between close relatives among these late Neandertals of North-Western Europe. Instead, these Neandertals were part of a larger and more well-connected regional population, quite different to what previously seen for Neandertals in Siberia. “Our results show that the picture emerging from one region cannot simply be applied to all Neandertals,” says senior author Benjamin M. Peter, a group leader at the Max Planck Institute for Evolutionary Anthropology. “The late Neandertals from North-Western Europe appear to have been part of a connected regional population, rather than small, isolated groups with frequent mating between close relatives.”

The study also reveals a more complex population history of Neandertals than previously recognised. “The genetic data show both connection and complexity,” says senior author Mateja Hajdinjak, a group leader at the Max Planck Institute for Evolutionary Anthropology. “Most late Neandertals from North-Western Europe are closely related at the population level, but some lineages point to much deeper and more diverse Neandertal history.”

The Neandertals in this study lived at a time when early modern humans were already present in parts of Europe. While genetic evidence indicates that Neandertals contributed genetic material to early modern humans, the researchers found no evidence of recent gene flow in the opposite direction. “Our results add to a striking asymmetry,” adds Bossoms Mesa. “We repeatedly find Neandertal ancestry in early modern humans, but so far, we have not found clear evidence of recent modern human ancestry in late Neandertals.”

Rethinking Neandertal extinction

The disappearance of Neandertals has often been linked to small population size, inbreeding, and the accumulation of harmful genetic variants. The new study tested this theory by comparing measures of genetic diversity and genetic load in Neandertal genomes from different time periods and regions. Although all Neandertals had very limited genetic diversity, the researchers found no evidence that the late Neandertals carried an increasing burden of harmful mutations, and when they compared the high quality genome of the Goyet Neandertal, her genome did not show lower diversity than earlier Neandertals.

These results do not rule out the possibility of demographic vulnerability, however, they challenge the idea that Neandertals disappeared mainly because their genomes steadily deteriorated. Instead, late Neandertals in Belgium and France appear to have been part of a connected, genetically diverse regional population during a period of profound ecological and demographic change.

“This study highlights the power of ancient DNA to reveal variation within Neandertals on a much finer scale than was previously possible,” says co-author Janet Kelso, a group leader at the Max Planck Institute for Evolutionary Anthropology. “Rather than viewing late Neandertals as a single declining population, we are beginning to recognise a more complex picture of regional diversity, connectivity, and population history.”