Isolated Neanderthal Population Found: 50,000 Years of Seclusion Revealed

As if Neanderthals weren’t already mysterious enough, groundbreaking research adds a startling new layer to our understanding of their final days. It appears some populations lived in total genetic and social isolation for more than 50,000 years. The study, conducted on an individual discovered in Grotte Mandrin in Mediterranean France, uncovers a “ghost lineage” that suggests Neanderthals were far more fragmented than we ever imagined. The Grotte Mandrin Neanderthals The Grotte Mandrin rock shelter in southern France has long been a treasure trove for archaeologists. It contains multiple sedimentary layers spanning tens of thousands of years, preserving the history of both Neanderthals and early modern humans. In 2015, during an excavation at the site, a remarkable find was made: the partial remains of a Neanderthal individual dubbed “Thorin.” The name is a direct reference to Thorin Oakenshield, the Tolkien character who was a “King under the Mountain” and leader of an ancient, displaced people. Lead researcher Ludovic Slimak chose this name to reflect the individual’s status as a remnant of a fading, ancient world—one of the last of a lineage that refused to change. Thorin’s remains, including cranial and dental fragments, date back to approximately 50,000 years ago. The site’s rich archaeological context provided evidence that Thorin lived during the final millennia of Neanderthal existence. But it wasn’t just this discovery that intrigued researchers. What made this find particularly significant was the genetic data recovered from his teeth, which tell a tale of stunning isolation. “The Thorin population spent 50,000 years without exchanging genes with other Neanderthal populations,” says co-first author and discoverer of Thorin, Ludovic Slimak, CNRS researcher of Université Toulouse III – Paul Sabatier. It’s not like this population was living far away from others either, says Slimak. “We have 50 millennia during which two Neanderthal populations, living about ten days’ walk from each other, coexisted while completely ignoring each other. This would be unimaginable for a Sapiens and reveals that Neanderthals must have biologically conceived our world very differently from us Sapiens.” So shocking the data seemed wrong Thorin was found in the same layer as other objects and structures from 40-45,000 years ago, so archaeologists estimated that that was Thorin’s age as well. But the genetic data suggested that Thorin was very different from Neanderthals who lived in that period and suggested the individual more closely resembled the genomes of Neanderthals who lived more than 100,000 years ago. “We worked for seven years to find out who was wrong — archaeologists or genomicists,” says Slimak. To resolve this, researchers used isotope analysis of Thorin’s teeth, which tracks the climate an individual lived in. The results confirmed he lived in a cold, late-glacial climate. This proved that Thorin was a “Late Neanderthal” possessing an “Early Neanderthal” genome. “This genome is a remnant of some of the earliest Neanderthal populations in Europe,” says population geneticist and senior author Martin Sikora of the University of Copenhagen. “The lineage leading to Thorin would have separated from the lineage leading to the other late Neanderthals around 105,000 years ago.” 50,000 Years of Solitude The shocking implication of this is that Thorin’s population spent 50 millennia in total isolation. Even though Thorin’s group lived in the same cave system that early Homo sapiens and “progressive” Neanderthals later occupied, they showed a profound cultural conservatism. They didn’t trade, adopt new tool technologies, or interact with “outsider” groups. Traditionally, Neanderthal extinction theories have focused on external factors, such as climate change, volcanic eruptions, or competition with modern humans. However, the genetic isolation of Neanderthal groups introduces the possibility that internal factors also played a critical role. The lack of interbreeding with other Neanderthal groups or early modern humans could have become an existential threat in time. This discovery suggests that, by the time Thorin lived, there were multiple, genetically distinct Neanderthal populations scattered across Europe. These populations might have been culturally and geographically close but genetically isolated, indicating a complex population structure among late Neanderthals. Why didn’t they interbreed at all for so long? It could be geographic barriers or climatic changes, but it could also be social behaviors that prevented these Neanderthal groups from interbreeding. Whatever the cause, this suggests that Neanderthal extinction wasn’t just caused by climate or violence, but by a social “bottleneck.” Their lack of curiosity about “the other” left them genetically vulnerable. Neanderthals are even more surprising than we thought The myth that Neanderthals were unthinking brutes has long been disproven. They appear to have been every bit as intelligent and culturally capable as humans. Yet the reasons for their disappearance are all the more mysterious. Thorin’s population was not the only isolated Neanderthal group during this period. Other Neanderthals, such as those from the Mezmaiskaya and Chagyrskaya caves in Siberia, also show signs of small group sizes and genetic isolation. Together, these findings suggest that Neanderthals were not a single, cohesive population but rather a collection of fragmented groups, each facing their own challenges. This cultural separation could have been another factor in the isolation of Neanderthal populations. While early modern humans likely had broader social networks and exchanged ideas and technologies across larger distances, Neanderthals appear to have been more limited in their interactions with other groups. Thorin’s population represents one of the last groups of surviving Neanderthals in Europe. As isolated as they were, these Neanderthals managed to persist until around 40,000 years ago, just before Neanderthals disappeared from the archaeological record. The discovery of Thorin’s genome suggests that these final populations were living in increasingly fragmented and isolated communities. They faced the pressures of inbreeding, environmental change, and competition with modern humans. By studying individuals like Thorin, researchers are beginning to piece together the final chapters of Neanderthal history. It is becoming increasingly clear that Neanderthal extinction was not a single event but rather the culmination of many factors. Long genetic and social isolation in Neanderthals before their extinction, Cell Genomics (2024). DOI: 10.1016/j.xgen.2024.100593. www.cell.com/cell-genomics/ful … 2666-979X(24)00177-0 This article was originally published in September 13, 2024, and has been reedited