Denisovan Fossils Are Resurfacing and Teaching Us More About Our Mysterious Human Cousins

Scientists have only had minimal DNA samples and bone fragments belonging to Denisovans to study, but recently, two new fossils have come out of hiding that reveal more about our elusive cousins

Hiya!

We modern humans are the only human species that exists today, but once upon a time, we shared the planet with at least five others — Homo heidelbergensis, Homo floresiensis, Homo erectus, Homo neanderthalensis (the Neanderthals), and Homo longi (Denisovans), the two latter of which, we actively coexisted with.

We know quite a lot about Neanderthals, as like us, they often buried their deceased. This practice helped protect their remains and allowed modern archaeologists to discover and study them. However, the Denisovans didn’t appear to do the same, and archaeologists have only found a few bone fragments, making this species much more mysterious. But two recent jawbones have resurfaced that shed more light on our elusive cousins.

Denisovans

In 2010, archaeologists unearthed several bones in Siberia’s Denisova Cave, near the Russian-Kazakhstan border, and sent them to Svante Pääbo, a paleogeneticist at the Max Planck Institute for Evolutionary Anthropology, and his team for further analysis.

Luckily for the scientists, the cave’s freezing temperatures preserved ancient DNA in some of the fossils, revealing that some were Neandertheral and some were Homo sapien fossils.

However, a pea-sized pinky bone, dating to over 60,000 years old, belonged to a previously unknown human species. Pääbo’s team nicknamed them the Denisovans, after the Denisova Cave in which the remains were found.

Incredibly, the cave also bequeathed a remarkable fossil (which I wrote about) containing DNA showing it belonged to a female who had a Neanderthal mother and Denisovan father, making her the only first-generation hybrid hominin ever discovered.

In addition to being a newly discovered branch of our Homo family tree, the Denisovans became the first human species to be identified exclusively through DNA — and their DNA can tell us a lot.

Gene Flow Events

From the small finger bone, Pääbo and his colleagues learned that Denisovans were likely more closely related to Neanderthals than us and that Denisovans and humans interbred — both of which have been reconfirmed.

Research shows that modern humans of Eurasian descent inherited between 1 and 4 percent of their genome from Neanderthals. It was once thought that people of African descent don’t have Neanderthal DNA, but, as I shared with you back in 2022, that’s since been debunked.

Meanwhile, individuals from Oceania of South Asian descent inherited up to 5 percent of their genome from Denisovans, particularly people with Papua New Guinea ancestry, an island that’s over 5,500 miles away from the Denisova Cave.

In fact, we Sapiens — as I will henceforth refer to us — have a long, long history of interbreeding with Neanderthals and Denisovans alike, going back to before the two species diverged evolutionary paths.

Evidence of our interbreeding habits with Neanderthals and Denisovans is so strong that paleoanthropologists now believe these “gene-flow events” were a key element of our Sapien evolution.

As the theory goes, swapping genetics with our hominin cousins may have given our ancestors new traits that helped them adapt to new environments.

This may be related to what scientists discovered in January 2025: that we, Sapiens, evolved new blood types after leaving Africa and interbreeding with Neanderthals. It seems plausible that something similar occurred when we interbred with Denisovans.

However, while such interbreeding worked to our advantage, interbreeding with us didn’t supply the same result for our cousins. As the Natural History Museum states:

The lack of mitochondrial DNA, which is inherited through females, from Neanderthals in living humans has been suggested as evidence that only male Neanderthals and female Homo sapiens could mate, but there is also some evidence that male hybrids may have been less fertile than females.

Further research suggests that some offspring with Neanderthal, but especially Denisovan, mothers and Sapien fathers had a now-rare blood disorder, called haemolytic disease of the foetus and newborn (HDFN).

HDFN occurs when a mother's and her baby's blood types are incompatible. As a result, the mother’s antibodies attack the fetus's and newborn’s red blood cells, causing them to break down quickly.

Thankfully, while it used to be a significant cause of fetal loss and death among newborn babies, HDFN is rare now thanks to technological and scientific advancements.

Anyway, while DNA can teach us a lot about the Denisovans, scientists require a bunch more fossils, ideally mostly intact ones, to better understand what they may have looked like, where they lived, and what physical attributes they may have had in common with us.

As luck would have it, such fossil remains are beginning to resurface. This article was initially inspired when I learned that a mandible (jaw) bone was recently confirmed to be Denisovan, but as I investigated, I learned of another one, and both provide new information that helps answer our questions.

The Xiahe Mandible