A Hidden Lineage: New Insights into Neanderthal Evolution

A New Discovery Sheds Light on Neanderthal Diversity

In a very groundbreaking, surprising study¹, researchers have revealed that European Neanderthals consisted of at least two distinct populations, evolving in isolation for tens of thousands of years. Long regarded as a relatively homogenous group, Neanderthals may have had a much more complex evolutionary history, characterized by local extinctions and migrations. This new finding challenges long-held assumptions about their genetic uniformity and underscores the diversity of hominid populations in prehistoric Europe.

The Neanderthal fossil was found in 2015 at the Grotte Mandrin rock shelter (shown) in France.

The Discovery of Thorin: A New Line of Neanderthals

The key to this revelation lies in the remains of an adult male Neanderthal, dubbed “Thorin,” found in 2015 at the Grotte Mandrin rock shelter in France. Thorin’s partial skeleton, excavated by a team led by archaeologist Ludovic Slimak of Université Toulouse III – Paul Sabatier, holds genetic clues that point to a previously unknown lineage of Neanderthals. This lineage, it seems, had evolved separately from other European Neanderthals for around 50,000 years, almost until their extinction approximately 40,000 years ago. Paleogeneticist Carles Lalueza-Fox, who was not involved in the study notes,

“Neanderthals likely had their own complex evolutionary history, with local extinctions and migrations, just like us.”

The Thorin Neanderthal (Top) View of the mandible in situwhen found in September 2019. (Bottom) Virtual reconstruction of the jaw and dental elements of Thorin in tilted (upper left), anterior (upper right), and lateral (bottom right and left) views.

Genetic Evidence Reveals a Divergent Neanderthal Lineage

Using sophisticated dating methods, researchers determined that Thorin lived between 50,000 and 42,000 years ago. Molecular analysis of his remains, including a molar, revealed that about 65% of Thorin’s genome could be recovered. When compared to DNA from other Neanderthals, early Homo sapiens, and modern humans, Thorin’s genetic profile stood out.

Allele sharing between Thorin and other known Neanderthals (Left) D-statistics of the form D (Altai Neanderthal, Vindija 33.19; Neanderthal X, Mbuti), showing that all Eurasian Neanderthal samples share more alleles with Vindija 33.19 than with the Altai Neanderthal. Thorin shares relatively more alleles with Vindija 33.19 than early European Neanderthals of the putative first radiation (HST, Scladina, Estatuas pit 1 layer 4), but less than the second radiation (Mezmaiskaya 1, Chagyrskaya 8). We used all reads obtained from each Neanderthal X case to maximize the resolution as contamination levels in general are low. Chagyrskaya 8 is, however, represented with diploid genotypes. (Right) D-statistics of the form D (Vindija 33.19, Thorin; Neanderthal X, Mbuti), showing that Neanderthals from Europe, the Caucasus, and Siberia younger than 80 ka share more alleles with Vindija 33.19 than with Thorin. The exception is the Gibraltar Neanderthal sample (FQ), which shows increased affinity with Thorin. We used all reads for each Neanderthal X and Thorin, while we represented Vindija 33.19 with pseudo-haploid genotypes. Error bars indicate 3× SE (|Z| = 3). Colors indicate the age of the individuals. Samples not directly dated or with uncertain dates are indicated with gray circles.

Thorin’s DNA more closely aligned with that of Neanderthals from around 105,000 years ago than with those from his own era. This suggests that Thorin belonged to a population that diverged from other European Neanderthals around 105,000 years ago, developing in relative isolation in southwestern Europe. Such isolation is supported by Thorin’s unusually high percentage of identical gene pairs, indicating inbreeding within a small population—a pattern previously observed in Siberian Neanderthals.

A Separate Line of Neanderthals in Southwestern Europe

This newly identified lineage of Neanderthals, to which Thorin belonged, seems to have lived in small, closely related communities that exchanged mates only within their own group. While it remains unclear why these Neanderthal communities avoided interbreeding with others, cultural or linguistic differences may have played a role.

Thorin’s DNA shares similarities with that of a Neanderthal fossil found in Gibraltar, suggesting that this isolated population may have stretched across parts of southwestern Europe. However, researchers caution that more evidence is needed to determine the precise age of the Gibraltar fossil, which was discovered in 1848. Paleogeneticist Cosimo Posth of the University of Tübingen says,

“If Thorin is really 50,000 years old, this would be an amazing finding, showing a strong genetic structure in late Neanderthals.”

What Does This Mean for Neanderthal Evolution?

Thorin’s discovery raises intriguing questions about the evolution and eventual extinction of Neanderthals. Was this isolated population able to survive for so long due to their remoteness, or did they face challenges that ultimately led to their demise? The team has not yet determined how Thorin’s body came to rest in the Grotte Mandrin or whether his remains were transported there from older sediment. Further excavations may help clarify these mysteries.

The findings also shed light on the broader question of Neanderthal diversity. As Thorin’s lineage demonstrates, Neanderthal populations were not as uniform as once believed. This complexity adds nuance to our understanding of how Neanderthals lived, interacted, and adapted to the challenges of their environment.

Looking Ahead: The Future of Neanderthal Research

To fully understand Thorin’s place in Neanderthal history, researchers are hoping to isolate more of his DNA and locate additional fossils from his lineage. As more data becomes available, scientists will be able to clarify how these close-knit communities evolved and whether their isolation led to their eventual extinction. Lalueza-Fox explains,

“Thorin’s DNA offers a glimpse into a Neanderthal world that we’re only beginning to understand. It’s clear that their story is much more complex than we ever imagined.”

This discovery not only challenges long-held beliefs about Neanderthals but also opens the door to new questions about the evolutionary history of our closest ancient relatives. With further research, the puzzle of Neanderthal diversity and survival will continue to unfold, offering fresh insights into the deep past of human evolution.

1. Sikora, M., Slimak, L., Hopfe, C., Feuerborn, T. R., Havik, B., Makowsky, R., … & Prüfer, K. (2024). A previously undescribed late Neanderthal lineage from the Grotte Mandrin site. Cell Genomics, 4(10), 100217. https://doi.org/10.1016/j.xgen.2024.100217