Why Did Neanderthals Go Extinct? Inbreeding Probably Wasn’t to Blame for Their Demise in Northwestern Europe, a Study Suggests

In contrast to those who resided in Siberia, Neanderthals who lived in what’s now Belgium and France shortly before the species vanished seem to have been genetically diverse and healthy

Sarah Kuta | Daily Correspondent

June 30, 2026 10:00 a.m.

Share

Copy linkEmailSMSFacebookXRedditLinkedInBlueskyPrint

Add as preferred source

Scientists have long puzzled over the disappearance of the Neanderthals, which went extinct roughly 40,000 years ago. A lack of genetic diversity resulting from inbreeding, competition with Homo sapiens, disease and changing climate conditions have all been proposed as possible explanations for their demise.

Now, a study published June 24 in the journal Nature suggests that inbreeding may not have been the primary driver of extinction for at least one group of Neanderthals.

Researchers analyzed DNA from the remains of 27 Neanderthals found at ten sites in northwestern Europe shortly before the species went extinct. From the remains of one individual, who lived in what is today Belgium around 45,000 years ago, they were able to sequence a high-quality genome, meaning they were able to reconstruct nearly the entire genetic code with a high degree of accuracy.

“Until now, we only had four high-quality Neanderthal genomes and a limited number of lower-quality ones, so most questions about the regional diversity of Neandertals have been difficult to address,” lead author Alba Bossoms Mesa, an evolutionary geneticist at the Max Planck Institute for Evolutionary Anthropology in Germany, says in a statement. “By generating genetic data from multiple individuals from the region of present-day Belgium and France, we can now examine late Neanderthal populations in much greater detail.”

The newly sequenced DNA suggests these Neanderthals were relatively genetically diverse, likely because they were members of a bigger, interconnected regional population. Additionally, the researchers found none of the genetic signals typically associated with recent mating between close relatives—such as increasing genetic deterioration or decreasing genetic diversity over time—a finding that suggests at least some groups of Neanderthals were not inbreeding.

“I am very happy to dispel the misconception that all Neandertals went extinct because they were too inbred,” Bossoms Mesa tells Live Science’s Charles Q. Choi.

However, as Carles Lalueza-Fox, a paleogenomicist at the Institute of Evolutionary Biology in Barcelona who was not involved with the research, writes in an accompanying commentary, it’s possible that the Neanderthals living in northwestern Europe “might not have had sufficient time to accumulate detectable signals of genetic erosion” before the species went extinct.

Additionally, Neanderthals lived across Europe and Asia for hundreds of thousands of years, so those living in northwestern Europe might have had very different experiences than those living elsewhere. For example, the remains of a Neanderthal woman discovered in Siberia—one of the handful of other high-quality Neanderthal genomes scientists have sequenced—show that her parents may have been half-siblings and that mating among close relatives was common among her recent ancestors, likely because those Neanderthals lived in smaller, more isolated groups at the edge of the species’ range.

Overall, the new findings support the idea that “the picture emerging from one region cannot simply be applied to all Neandertals,” study co-author Benjamin M. Peter, an evolutionary geneticist at the Max Planck Institute for Evolutionary Anthropology, says in the statement. Study co-author Janet Kelso, also an evolutionary geneticist at the Max Planck Institute for Evolutionary Anthropology, echoes that sentiment.

“Rather than viewing late Neandertals as a single declining population,” she says in the statement, “we are beginning to recognize a more complex picture of regional diversity, connectivity and population history.”

If the Neanderthals living in northwestern Europe shortly before extinction were genetically healthy, then what ultimately caused them to die out? Scientists weren’t able to answer that question with this new paper, so for now, it remains “a mystery,” Fernando Villanea, a geneticist at the University of Colorado Boulder who was not involved with the study, tells Science’s Michael Price. “I’m excited for someone to put the pieces together.”

The newly sequenced genetic material also raises a perplexing question about Neanderthals. Scientists know that some Neanderthals interbred with H. sapiens, which is why most humans alive today have trace amounts of Neanderthal DNA. And the Neanderthals included in the study likely overlapped with H. sapiens for years—possibly for as many as 500 generations. Yet the researchers found no evidence of recent H. sapiens DNA in the Neanderthals living in northwestern Europe.

“We have several examples of early modern humans who had a Neanderthal ancestor only a few generations back. In some cases, a Neanderthal was effectively their great-great-great-grandparent,” Bossoms Mesa tells IFLScience’s Tom Hale. “By contrast, we do not yet have a single confirmed example of a Neanderthal individual with a recent modern human ancestor in their family tree.”

What could explain this asymmetry? Perhaps the Neanderthals in northwestern Europe chose to ignore or avoid H. sapiens, per Science. It’s also possible that genetic incompatibilities prevented H. sapiens DNA from entering the Neanderthal gene pool more broadly.

But scientists suspect social or cultural factors might also have been at play. “Imagine that modern humans were willing to raise and incorporate into the community a baby who was half Neanderthal and half human, but Neanderthals were not,” Bossoms Mesa tells El País’ Daniel Mediavilla.

Sarah Kuta | Read More

Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.