A duo of Denisovan skull fragments that fit into the palm of one’s hand have been found in the first ever discovery of its kind. The finding comes with only a few other fossils previously uncovered from this enigmatic group of extinct hominids, including that of a finger bone, two teeth, and a milk tooth from a young girl.
The verification was made possible by the extraction of mitochondrial DNA – inherited genetic material from the mother – from the skull, according to paleoanthropologist Bence Viola, who presented the findings on Thursday at the 88th Annual Meeting of the American Association of Physical Anthropologists.
The little-known Denisovans are an Asian sister group of the Neanderthals, whose genes have contributed to the genetics of modern humans in large parts of Asia and in Melanesia.
It’s believed Denisovans periodically occupied Denisova Cave from around 300,000-50,000 years ago, with Neanderthals also inhabiting it for some time. The cave in the Altai Mountains of Siberia is a goldmine for research on these people, with no other fossils from anywhere else in the world definitively identified as Denisovan.
These two pieces – together dubbed Denisova 13 – were found in 2016 from the South Gallery of Denisova Cave. This section collapsed in, making its stratigraphic position inconclusive. The team, therefore, tentatively describe it to layer 22 based on its preservation and accompanying sediments.
The fragments form part of the left parietal bone, the region forming the central upper-back part of the skull between the frontal and occipital bones.
In another study at the annual meeting, Murray Cox and colleagues also analyzed the genomes of over 160 people from 14 groups in Island Southeast Asia and Papua using three statistical methods. Intriguingly, they discovered that Papuans contain the DNA of two deeply divergent Denisovan lineages, which the team called D1 and D2. These populations are almost as distantly related to each other as they are to Neanderthals.
The discovery reinvents the notion that Denisovans were a single population, with multiple populations hinted at previously but with even more evidence now. The Denisovans, it seems, have many secrets yet to reveal.