A lifelike museum reconstruction of a Neanderthal hunter crouching outdoors among rocks and fallen leaves, using a stone tool to process a small animal carcass. He wears animal fur and has long dark hair and a facial marking.
Photo Credit: Pressebilder Neanderthal Museum, Mettmann/Wikimedia Commons
Scientific Frontline: Extended "At a Glance" Summary: Late Neanderthal Population Genetics
The Core Concept: A recent genetic analysis of late Neanderthals (Homo neanderthalensis) in Western Europe indicates that these populations were genetically diverse, healthy, and interconnected just before their extinction.
Key Distinction/Mechanism: Unlike earlier Neanderthal populations that showed severe signs of inbreeding, individuals from the Meuse Basin around 45,000 years ago displayed no evidence of "inbreeding depression" or genetic mixing with anatomically modern humans (Homo sapiens).
Origin/History: Neanderthals survived across Eurasia for hundreds of thousands of years before vanishing approximately 40,000 years ago. This study analyzed ancient DNA extracted from the bones of 27 individuals who lived between 49,000 and 40,000 years ago in present-day Belgium and France.
Major Frameworks/Components:
- Genetic Diversity Analysis: Researchers examined stretches of DNA for identical base pairs to detect inbreeding, which can compromise a population's adaptability, disease resistance, and fertility.
- Lineage Tracking: Mitochondrial DNA revealed a common maternal lineage coexisting with a distinct alternative lineage, while Y-chromosome data indicated diverse paternal ancestry among the males.
- Kinship Limitations: Advanced computational methods established that the sampled individuals shared no closer than third-degree relatedness (approximately 12.5% shared DNA), a level comparable to first cousins.
Branch of Science: Evolutionary Biology, Population Genetics, Biological Anthropology, and Paleogenomics.
Future Application: The novel computational techniques developed to extract and analyze this specific degraded ancient DNA can be applied to other archaic genomes, significantly improving researchers' ability to reconstruct prehistoric population dynamics and migrations.
Why It Matters: These findings demonstrate that genetic decline was not a universal precursor to the Neanderthal extinction. The sudden disappearance of this thriving, interconnected population points to rapid external pressures, such as abrupt climatic shifts or sudden resource competition, rather than an internal genetic collapse.
Neanderthals thrived across Europe and the Middle East for hundreds of thousands of years. They occupied vast distances, ranging from Europe through the Altai Mountains in Central Asia. They survived large variations in climate and the arrival of modern humans until around 40,000 years ago, when they died out. The exact factors that resulted in their disappearance remain unknown, with possible explanations including climate change, resource competition, and interbreeding with anatomically modern humans.
A new study published in Nature reveals that a Neanderthal population living around 45,000 years ago in Belgium and France was thriving, with no signs of inbreeding, pressure from, or genetic mixture with modern humans, who lived in the area at that time. The finding suggests that localized Neanderthal groups in this region were large and well-connected enough that individuals could have children with partners who were not closely related. Nonetheless, around 2,000 years later, even this population vanished.
“In other, earlier Neanderthal populations, close relatives were interbreeding, leading to unhealthy levels of genetic diversity similar to what we see today in some endangered species. But this population in Belgium and France does not seem to be dying out, even though we know that they will die out in the end,” said UCLA computational geneticist Benjamin Peter, one of the paper’s corresponding authors.
The research examined DNA extracted from the bones of 27 individuals who lived between 49,000 and 40,000 years ago in the Meuse Basin, which spans Belgium and France, using established computational techniques for studying ancient DNA and a new technique the researchers developed for these particular samples. They found no close relatives among any of the individuals up to third-degree relatedness—a level at which individuals share about 12.5 percent of their DNA, which was the limit of what their methods could detect. This is comparable to the amount of DNA shared between first cousins.
The mitochondrial DNA, which is inherited only from the mother, showed that most individuals belonged to a large lineage common to late Neanderthals in southern and southwestern Europe. This means that all these individuals shared female ancestors. One individual, however, belonged to a different maternal lineage found in a handful of other Neanderthals, suggesting that more than one of these mitochondrial lineages coexisted. Conversely, data from the Y chromosomes of three male individuals, which are passed on from father to son, showed that they did not belong to a single lineage, meaning that they each had different male ancestors.
To study the amount of genetic diversity, the researchers looked for stretches of DNA that contained identical base pairs. This occurs when a person inherits copies of the same genes from both parents, which is much more likely when the parents are related. When close relatives reproduce over time—a situation likely when a population is small and isolated—eventually most of the population will end up having similar genes, which will show up as long stretches of identical pairs on the DNA strands.
This reduction in genetic diversity, which population geneticists call “inbreeding depression,” means that harmful genes are more likely to be passed on; this reduces the potential to adapt to changing environments or respond to new diseases, and it may cause lower fertility. All of these factors make it harder for a population to survive and reproduce, and without an influx of new genes, they can lead to the population’s extinction.
“I think the most interesting finding we made is that these Neanderthals are genetically relatively healthy, with no strong signs that there was inbreeding depression,” said Peter, who conducted the research as a group leader at the Max Planck Institute for Evolutionary Anthropology and is now a UCLA assistant professor of ecology and evolutionary biology and at the Institute for Quantitative and Computational Biology. “It’s also interesting that we didn’t find evidence that they have ancestry from anatomically modern humans, even though we know that at least they must have overlapped in time.”
A final point of interest was the finding that all of the remains from one site, Goyet, were of unrelated females, juvenile males, and one newborn baby.
Taken together, the genetic analysis shows that although this Belgian population was more closely related to each other than to other Neanderthal groups, the difference was not substantial, suggesting there may have been considerable movement among these western Neanderthal groups.
“Over the very long time scale that Neanderthals existed in Eurasia, their entire range was not inhabited consistently. There were probably some areas where Neanderthals could survive through climatic events like ice ages, and they expanded into other areas when conditions were suitable for human habitation,” said Peter. “It seems that Western Europe at this time was a good place to be a Neanderthal. I think a climate shift later on, and maybe competition from modern humans, or a combination, led to the extinction very soon after the individuals that we studied.”
Published in journal: Nature
Title: Genetic diversity of late Neanderthals in northwestern Europe
Authors: Alba Bossoms Mesa, Elena Essel, Stéphane Peyrégne, Arev P. Sümer, Leonardo N. M. Iasi, Christian Heide, Divyaratan Popli, Cesare de Filippo, Marie-Theres Gansauge, Lars Gerullat, Laurin Lippik, Sarah Nagel, Birgit Nickel, Barbara Schellbach, Anna Schmidt, Johann Visagie, Antje Weihmann, Hugo Zeberg, Julia Zorn, Hélène Rougier, Isabelle Crevecoeur, Patrick Semal, Grégory Abrams, Thibaut Devièse, Stéphane Pirson, Kévin Di Modica, Pierre Cattelain, Christelle Draily, Michel Toussaint, Isabelle De Groote, Frido Welker, Cosimo Posth, Marie Soressi, Jean-Jacques Hublin, Johannes Krause, Svante Pääbo, Matthias Meyer, Janet Kelso, Benjamin M. Peter, and Mateja Hajdinjak
Source/Credit: University of California, Los Angeles | Holly Ober
Edited by: Scientific Frontline
Reference Number: ebio062426_01
.jpg)