Scientists have stumbled upon the oldest fossil remains known to us today of the still rather mysterious Denisovans in the Denisovan Cave.

In recent centuries, much research has been done into the evolutionary history of humans. Using fossil remains found in various places on Earth, researchers have identified new hominids and placed them in our extensive family tree. Some of those humanoids – like Australopithecus afarensis, aka Lucy or Ardipithecus ramidus, aka Ardi – lived long before Homo sapiens saw the light of day. Others—such as Neanderthals and the recently discovered Denisovans—must have lived with our distant ancestors. Our knowledge of the different hominids varies widely. We know a lot about some species (that applies to the Neanderthal, for example). Others remain quite mysterious.

Mysterious

The Denisovans can also be counted among the latter mysterious species. This can largely be traced back to the fact that few fossil remains of this hominin have been found (see box).

The first remains of the Denisovans (or Homo denisova, as they are officially referred to) were presented in 2010. It was a phalanx and molar that had been discovered two years earlier in the Siberian Denisova cave. After thorough investigation, researchers had to conclude that the remains of an unknown hominin were named after the cave in which the remains were found. In the years that followed, a few more molars and fragments of a bone from the skull and a bone from an arm or leg were found in the same cave. In 2019, remains of Denisovan people were also found outside the Denisovan cave for the first time; in a Tibetan cave, researchers stumbled upon a Denisovan’s lower jaw.

However, an international team of researchers is now featured in the magazine Nature Ecology with good news. They have again discovered remains of Denisovan people in the Denisovan cave. And not just any remains, but the oldest fossil remains of this hominin that have been found to date. It concerns three fragments of bones that are about 200,000 years old.

Lots of bone fragments

Judging by previous finds, it was of course to be expected that the Denisovan cave contains even more remains of Denisovan people. But detecting them is a lot more difficult than you might think. In addition to bone fragments from Denisovans, the cave also contains hundreds of thousands of bone fragments from animals. And many of those fragments are so small that it’s impossible to determine from appearance alone whether they belonged to animals or humanoids. And yet researchers have now succeeded in pointing out some bone fragments of Denisovans among all those bones. To this end, they examined nearly 3,800 bone fragments that were no more than 4 centimeters long and were extracted from the oldest layers of soil in the cave. These bones had previously been determined to be too fragmented to be identified. However, the researchers were not guided by external features, but focused on the proteins that could be found in the bone fragments. In doing so, they specifically looked for proteins that, thanks to previous research, we know only occur in hominins. It enabled the researchers to identify five human-like bone fragments among those thousands of bones. “Finding one new humanoid bone would have been really cool, but five? That really exceeded my wildest expectations,” said researcher Samantha Brown. “We were stunned to discover new humanoid bone fragments harboring intact biomolecules in such ancient soil layers,” added researcher Katerina Douka.

Three bone fragments of Denisovan people

Of the five bone fragments, four harbored enough authentic DNA fragments to be further identified. Follow-up research revealed that three of these four bones had belonged to Denisovans. The fourth bone fragment is from a Neanderthal.

200,000 years

The recovered bone fragments of Denisovans are also dated. And it turns out that they are about 200,000 years old. This makes them by far the oldest Denisova bones discovered to date.

The first inhabitants of the cave

Since the bone fragments come from the oldest layers in the cave, the find can also be used to gain more insight into the life of the first Denisovans who settled in southern Siberia. For example, the Denisovans appear to have appeared here during an interglacial, i.e. a warmer period between two colder epochs. According to the researchers, the fact that they were actually in the Denisova cave has everything to do with the cave’s strategic location. Furthermore, an analysis of animal bone fragments dating from the same period indicates that the first Denisovans hunted herbivores such as bison, roe deer, red deer and even woolly mammoths. They must have lived like this for several thousand years in a row.

It seems likely that the Denisovan Cave can tell us much more about the mysterious Denisovan people. After all, scientists now have a method by which bone fragments that were previously thought to reveal little to us can still be used to put an end to the mysterious character of the Denisovans. “Using this has enabled us to find more hominid fossils than a ‘regular’ archaeological dig,” said researcher Tom Higham. “That is a huge technical breakthrough for Paleolithic archaeology.”