Humans
PUBLISHED
The first confirmed arm bone of a Denisovan has been discovered in southwest China, adding another piece to the puzzle of an elusive human relative that once walked the Earth alongside our own kind.
Only a handful of physical Denisovan remains have ever been knowingly recovered, including finger bones, ribs, teeth, jawbones, some skulls, and a couple of leg bones. But now, researchers in China report they have discovered the first Denisovan radius, one of the two long bones in the forearm.
The treasure trove in Bianfu Cave
The new fossil was identified under pretty remarkable circumstances. In Yunnan, southwestern China, there’s a site called Bianfu Cave that contains more than 60,000 bone fragments found in several layers of sediment – an archaeological needle in a haystack.
The vast majority of these skeletal remains belonged to non-human animals, but researchers used a novel method to identify 22 potential hominin remains, dated to around 167,000 to 134,000 years ago.
The team then looked closely at proteins within the bone (a technique called proteomic analysis) to reveal that at least seven of these hominin remains contained a distinct amino acid variant associated with Denisovans.
Among the collection were two skull fragments and four teeth, but the most incredible specimen was a chunk of radial bone, a rare limb bone to add to the sparse collection of known Denisovan remains.
It has been speculated that the bone used to identify Denny, a hybrid female who had a Neanderthal mother and a Denisovan father, may have come from her leg or an arm. However, this discovery in Bianfu Cave is believed to be the first confirmed instance of an arm bone from a Denisovan.
It's also significant because the site is deep in southern China, far further south than other remains, most of which are found in Siberia or northern regions of China. Genetic evidence has hinted that Denisovans might have hung out closer to the tropics across Southeast Asia and Oceania than the limited fossil evidence has suggested so far, but physical evidence has remained intriguingly scant.
The personal lives of Denisovans revealed
In an accompanying study, another team of Chinese scientists looked at the wider archaeological context of the Bianfu Cave by piecing together over 1,300 stone artifacts found here, all dated to somewhere between 190,000 and 70,000 years ago.
Their research shows that Denisovans were prolific tool-makers, crafting bits of animal bone and stone to fashion all kinds of objects to help them master their surroundings. Many appear to be sharpened hunting weapons, designed to take down the medium- and large-sized mammals that once roamed this part of East Asia.
Perhaps most significantly, the tools have a strong similarity to the technology being developed by Neanderthals at the time. This suggests some form of cultural exchange between the two extinct hominins, although that’s not wholly surprising given their geographical overlap and close genetic similarity.
The researchers additionally managed to get their hands on samples of prehistoric pollen in the cave sediment, shedding light on the natural environment at the time it was inhabited. It indicated that the Denisovans lived in a rich forest-like environment, dominated by conifers.
As a whole, the two studies suggest the Bianfu Cave has the richest Denisovan fossil record currently known outside Denisova Cave in Siberia, the place where these enigmatic hominins were first identified in 2010.
Tiny bits of bone can only tell us so much about the Denisovans, even if they're packed full of genetic information to unravel; but at sites like Bianfu Cave, we start to see a deeper, more rounded view of their lives and identity.
The two new studies are published in the journal Nature (here and here).
