A new DNA study has found that two Neanderthals who lived about 10,000 years apart at the same cave in Siberia were distant relatives, offering fresh insight into how these ancient humans lived in small and connected groups.
Researchers analyzed a tiny bone fragment, about 110,000 years old, discovered in Denisova Cave. The fragment provided the fourth complete Neanderthal genome ever recovered. The findings were published March 23 in the Proceedings of the National Academy of Sciences.
Genetic link across thousands of years
Scientists studied the genome of a Neanderthal male, known as D17, and compared it with other sequenced Neanderthals, including a female called D5 who lived around 120,000 years ago at the same site. The analysis showed that D17 and D5 were not direct ancestors of each other. However, they shared a common ancestor and belonged to closely related lineages.
Researchers say this connection points to a long-term Neanderthal presence in the Altai region, even though different groups lived there at different times.
Cave used by multiple groups over time
Denisova Cave was not home to a single, continuous population. Instead, scientists believe different Neanderthal groups returned to the site over thousands of years. Diyendo Massilani, a genetics professor at Yale School of Medicine and lead author of the study, said the cave was likely part of a broader landscape used repeatedly rather than a permanent settlement.
Small and isolated populations
The study found that Neanderthals in the region lived in very small and isolated groups. Genetic evidence showed large sections of identical DNA, which indicates close relationships between parents, sometimes as close as first cousins. Researchers estimate these groups may have included fewer than 50 individuals.
A new DNA study shows two Neanderthals who lived 10,000 years apart in Siberia were closely related. The finding reveals small, isolated groups that stayed connected over time and reshapes how scientists understand Neanderthal life and survival. pic.twitter.com/PIR59SfdbG
— Tom Marvolo Riddle (@tom_riddle2025) April 2, 2026
Earlier studies support this pattern. One analysis suggested an Altai group may have had only about 20 individuals. Another found evidence of a population that remained isolated for tens of thousands of years.
Rapid genetic differences between groups
The research also revealed clear genetic differences between Neanderthal populations. D17 was more closely related to D5 than to Neanderthals from Europe or to later groups in the same region. This suggests that populations in eastern and western Eurasia became genetically distinct over a relatively short time.
Researchers say the level of separation is notable. Although the individuals studied were separated by about 50,000 years, their genetic differences were similar to those seen between some modern human populations that split much earlier.
What the findings mean for Neanderthal survival
Scientists have long linked isolation and inbreeding to the disappearance of Neanderthals around 40,000 years ago. However, the new findings show that these groups were able to survive for long periods despite small population sizes.
Researchers say this study adds to growing evidence that Neanderthals lived in scattered but connected groups. With more genomes now available, scientists are gaining a clearer picture of how these populations were structured and how they adapted to life across Eurasia.
