In 2015, archaeologist Ludovic Slimak made a groundbreaking discovery in a rock shelter of France's Rhône Valley: five Neanderthal teeth, the first complete remains of this ancient species found in France since 1979. Dubbed "Thorin" after a character from "The Hobbit," these teeth held secrets that would take nearly a decade to unravel, as they seemed to date back 105,000 years based on genetic analysis, yet the archaeological context suggested a younger age of 40,000 to 50,000 years.

The research, finally published in Cell Genomics, revealed that Thorin was part of a Neanderthal lineage that had been genetically isolated for approximately 50,000 years. This isolation explained the discrepancy in dating, as Thorin's DNA appeared older than it was. The study challenged the previous belief in a single, genetically homogeneous Neanderthal population at the time of their extinction, suggesting instead the presence of at least two distinct populations in Western Europe.

Slimak's findings point to small, insular Neanderthal communities, which, due to their isolation, may have faced difficulties in adapting to environmental changes or diseases and in sharing knowledge and technology. This insularity, along with the arrival of Homo sapiens in Europe, could have contributed to the Neanderthals' demise around 40,000 years ago. While interbreeding between Homo sapiens and Neanderthals left traces in present-day human DNA, no such genetic evidence has been found in Neanderthal fossils, including Thorin's.

The excavation at Grotte Mandrin, where the remains were found, is ongoing, with archaeologists meticulously uncovering the site. More of Thorin's remains have been discovered, including additional teeth, a part of the jaw, and finger bones, further hinting at a possible inbred population. The initial genetic analysis, which suggested an older age for Thorin, was later refined through the study of chemical isotopes in his bones and teeth, which helped infer the climate he lived in.

The mystery of Thorin's age and the story of his people continue to shed light on the complex narrative of Neanderthal extinction, a tale that is still being pieced together by dedicated researchers like Slimak, who has worked on the Grotte Mandrin site for over three decades. This site, with its alternating evidence of both Homo sapiens and Neanderthal habitation, continues to offer invaluable insights into our deep human past.