9 Facts About the Denisovans, Our Mysterious Human Ancestor

Only a handful of fossilized bones have ever been found to establish the Denisovans in the human family tree. But their DNA is revealing a lot about the extinct hominins.
A replica of the Denisovan finger bone discovered in 2010.
A replica of the Denisovan finger bone discovered in 2010. / Thilo Parg, Wikimedia Commons // CC BY-SA 3.0

Only a handful of tiny fossils of the Denisovans—human ancestors who went extinct about 30,000 years ago—have ever been discovered. Yet, thanks to advances in DNA analysis, scientists have uncovered intriguing clues about their lives. Read on for nine facts about the mysterious Denisovans.

The Denisovans were discovered in 2010.

Today, all modern humans are Homo sapiens, but as a species we have taken millennia to evolve. The very earliest human ancestors (a.k.a. hominins) emerged around 7 million years ago, while species in our genus, Homo, began appearing about 2.3 million years ago. Within the last 150 years or so, scientists have discovered evidence for at least eight different hominins in Homo, from Homo erectus, the first to migrate out of Africa, to the tiny Homo floresiensis, who stood only 3 feet, 6 inches tall.

In 2010, Russian scientists Michael Shunkov and Anatoly Derevianko unearthed a tiny finger bone in the Altai Mountains in southern Siberia. The fragment was sent to the Max Planck Institute in Germany for DNA analysis, where a team led by paleogeneticist Svante Pääbo determined that the bone came from an unknown type of archaic human, closely related to both Homo sapiens and Homo neanderthalensis.

Denisovans are named after a famous cave.

The entrance to Denisova Cave in Russia’s Altai Mountains.
The entrance to Denisova Cave in Russia’s Altai Mountains. / Демин Алексей Барнаул, Wikimedia Commons // CC BY-SA 4.0

The first bone fragment was found in the Denisova cave, which lent its name to the mysterious hominins. This incredible site is the only place in the world known to have been occupied by more than one hominin group. Fossils and debris from the many layers of cave floor provide evidence that the cave was inhabited by Denisovans roughly 200,000 years ago, by Neanderthals 100,000 years ago, and by modern humans. At some point, the two groups of extinct hominins may have coexisted there.

Fewer than a dozen Denisovan fossils have ever been found.

The Denisovans are especially mysterious because archaeologists have uncovered so few fossils, meaning that we don’t really know what they looked like. The only known fossils so far confirmed as Denisovan include three loose teeth, a skull fragment, a finger bone, half of a broken jawbone, and four other small slivers of bone. The remains were identified as Denisovan by protein or DNA analysis rather than morphology, and fascinating questions about the physical characteristics of these ancient human ancestors are still to be answered.

Scientists continue to search for more Denisovan bones. Fossils found in China, Taiwan, and Kyrgyzstan are thought to be likely contenders; however, their poor quality have precluded any DNA extraction and analysis. At this stage, it’s unclear if they are Denisovan or belong to another hominin group.

The Denisovans might be a new species—or they might not be.

The Denisovans are the only hominin identified as distinct from other hominins by DNA alone. Because so few of their fossils have been found—and because the ones we have are mere fragments—scientists haven’t determined the anatomy of a Denisovan. Without the physical description, they can’t be confirmed as a new species or subspecies. For now, Denisovans are considered a “population” in the genus Homo.

Neanderthals and Denisovans share a common ancestor.

Researchers looking at human evolution have suggested that the human ancestor Homo heidelbergensis, which lived between 600,000 and 300,000 years ago, left Africa about 400,000 years ago. Some moved west into Europe and likely evolved into Neanderthals, while others traveled into central Asia and became the Denisovans.

Hominin groups that remained in Africa evolved into Homo sapiens. By 60,000 years ago, this group had also migrated into Europe and Asia, and lived alongside Neanderthals and Denisovans for several thousand years.

Denisovans interbred with Homo sapiens and Neanderthals.

In 2018, analysis of a bone fragment found in Siberia revealed that it came from a teenage girl with a Neanderthal mother and a Denisovan father, providing the only known evidence of a first-generation hybrid hominin. The girl, nicknamed “Denny,” was thought to have lived 90,000 years ago. DNA evidence shows that Denisovans, Neanderthals, and modern humans were related closely enough that they could interbreed and bear children, and that Neanderthals and Denisovans were more closely related to each other than to Homo sapiens.

Traces of Denisovan DNA have been found in modern humans.

The fossilized remains of Denisovans come from just two locations, Siberia and Tibet (though a tooth found in Laos may also be Denisovan). Their genetic legacy, however, suggests they inhabited large swaths of Asia. DNA analysis of modern humans in Southeast Asia shows that many people have traces of Denisovan DNA, suggesting modern humans in the region interbred with Denisovans many thousands of years ago and indicating that they lived much farther south than had been initially thought.

Genetic evidence from Papua New Guinea hints that some modern humans may have interbred with Denisovans as recently as 25,000 years ago, implying that Homo sapiens and Denisovans coexisted in these areas for thousands of years. Today, the Indigenous Ayta Magbukon people in the Philippines, modern New Guineans, and Aboriginal Australians may be able to attribute 5 or 6 percent of their genes to Denisovan DNA.

Denisovan genes may have given modern humans some advantages.

Six views of an ancient tooth, possibly Denisovan, discovered in Laos.
Six views of an ancient tooth, possibly Denisovan, discovered in Laos. / F Demeter et al, Nature Communications // CC BY 4.0

The Denisovans lived harsh environments, from the cold, frozen steppes of Siberia to the high altitudes of Tibet. The excavations in Laos also suggest that some Denisovan communities lived in the lush tropical woodlands of Southeast Asia. The variety of the Denisovans’ habitats implies that they readily adapted to the climates in which they migrated and settled. In fact, scientists working in Tibet found that modern Tibetans may have inherited a Denisovan gene that helped them adapt to the low-oxygen environment at high altitudes.

No one is sure why the Denisovans died out—or when.

Some scientists suggest that Denisovans went extinct as recently as 20,000 years ago. They may have died out due to extensive interbreeding with other hominins, meaning that they slowly became absorbed into the wider human population. It’s also possible that as Homo sapiens encroached on Denisovan habitats, they outcompeted them for food, or introduced deadly diseases that contributed to the Denisovans’ demise. In the future, if more Denisovan remains are identified, archaeologists may be able to discover more answers to these elusive early hominins.

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