CLEVELAND — A palm-sized section of a braincase is the first Denisovan skull fossil ever found.
Discovered in two pieces in Siberias Denisova Cave in August 2016, the find joins only a handful of fragmentary fossils from these mysterious, extinct hominids. Mitochondrial DNA, a type of genetic material typically inherited from the mother, extracted from the skull pegged it as Denisovan, paleoanthropologist Bence Viola said March 28 at the annual meeting of the American Association of Physical Anthropologists.
Violas presentation was one of several at the meeting that raised new questions about these Neandertal relatives — including how recently they existed — who are known only from previous discoveries in Denisova Cave. A decade ago, a tiny part of a finger bone yielded Denisovan DNA that proved crucial to identifying the Stone Age population. Sediment analyses indicate that Denisovans periodically inhabited Denisova Cave from around 300,000 to 50,000 years ago, with Neandertals reaching the cave after around 200,000 years ago (SN: 3/2/19, p. 11).
But little else is known about Denisovans evolutionary history or identity. Its long been unclear, for instance, if Denisovans belonged to a distinct Homo species. And most researchers say that the new evidence is still not enough to resolve that mystery.
“Were a long way from solving the species question about Denisovans,” said paleoanthropologist Chris Stringer of the Natural History Museum in London, who gave a talk at the meeting on whats known about the group.
Viola, of the University of Toronto, and his colleagues compared a digital reconstruction of the skull fragment with corresponding parts of 112 present-day human skulls and 30 Stone Age Homo skulls, including Homo sapiens and Neandertals. The Denisovan find didnt fit neatly into any previously known Homo species. Some features linked the Denisovan fossil to Neandertals and to a 430,000-year-old Spanish Homo species that had Denisovan ancestry (SN: 12/28/13, p. 8). The Denisovan skull fragment is surprisingly thick, more like cranial bones of Stone Age Homo erectus, Viola said.
Such evidence is tough to interpret at this point, paleoanthropologist María Martinón-Torres of University College London said at the meeting. Interbreeding of closely related populations, such as Denisovans, Neandertals and H. sapiens, generates novel skeletal features that can obscure what started out as, say, a distinctive Denisovan look, she suggested.
Whatever evolutionary niche these mysterious hominids occupied, at least three separate Denisovan populations interbred with ancient humans, population geneticist Murray Cox of Massey University in Palmerston North, New Zealand, also reported at the meeting. Genetic remnants of two of those populations appear in modern aboriginal groups in Papua New Guinea, Cox and his colleaRead More – Source