The Denisovans are what scholars are calling a newly identified hominid species, separate from both early modern humans and Neanderthals. The only evidence of Denisovans recovered to date are a few fragments of bone, found in the Initial Upper Paleolithic layers of Denisova Cave, in the northwestern Altai Mountains some six kilometers (~four miles) from the village of Chernyi Anui, Siberia, Russia. But the fragments hold DNA, and the sequencing of that genetic history has important implications for the human habitation of our planet.
Human Remains at Denisova
The only remains of the Denisovans identified to date are two teeth and a small fragment of finger bone from Level 11 at Denisova Cave, a level dated between ~29,200-48,650 years ago and containing a variant of initial Upper Paleolithic cultural remains found in Siberiai called Altai. Discovered in 2000, these fragmentary remains have been the target of molecular investigations since 2008. The discovery came after researchers led by Svante Pääbo at the Neanderthal Genome Project at the Max Planck Institute for Evolutionary Anthropology successfully completed the first mitochondrial DNA (mtDNA) sequence of a Neanderthal, proving that Neanderthals and early modern humans are not very closely related at all.
In March 2010, Pääbo's team reported (Krause et al.) the results of the examination of one of the small fragments, a phalanx (finger bone) of a child aged between 5 and 7, and found within Level 11 of Denisova Cave. The mtDNA signature from the phalanx from Denisova Cave is significantly different from both neanderthals or early modern humans (EMH). A complete mtDNA analysis of the phalanx was reported in December of 2010 (Reich et al.), and it continued to support the identification of the Denisovan individual as separate from both neanderthal and EMH.
Pääbo and colleagues believe that the mtDNA from this phalanx is of a descendant of people who left Africa a million years after Homo erectus, and half a million years before the ancestors of Neanderthals and EMH. Essentially, this tiny fragment is evidence of a human migration out of Africa that scientists were completely unaware of before this discovery.
The Molar
The mtDNA analysis of a molar from Level 11 in the cave and reported in December 2010 (Reich et al.) revealed that the tooth was likely from a young adult of the same hominid as the finger bone: and clearly a different individual, since the phalanx is of a child.
The tooth is an almost complete left and probably third or second upper molar, with bulging lingual and buccal walls giving it a puffy appearance. The size of this tooth is well outside the range for most Homo species, in fact it is closest in size to Australopithecus: it is absolutely not a neanderthal tooth. Most importantly, the researchers were able to extract DNA from the dentin within the root of the tooth, and preliminary results reported (Reich et al.) its identification as a Denisovan.
Genome Sequencing
In 2012 (Meyer et al.), the mapping of the complete genome sequencing of the tooth was reported by Pääbo's team (Meyer et al.). The Denisovan, like modern humans today, apparently shares a common ancestor with Neanderthals, but has a completely different population history. While Neanderthal DNA is present in all populations outside of Africa, Denisovan DNA is only found in modern populations from island Southeast Asia and Oceania.
According to the DNA analysis, the families of present-day humans and Denisovans split apart about 800,000 years ago, and then reconnected some 80,000 years ago. Denisovans share the most alleles with Han populations in southern China, with Dai in northern China, and with Melanesians, Australian aborigines and other southeast Asia islanders.
The Denisovan individuals found in Siberia carried genetic data that matches that of modern humans and is associated with dark skin, brown hair and brown eyes.
The Denisovans
What we know about the culture of the Denisovans is that it was apparently not much different from other Initial Upper Paleolithic populations in the Siberian north. The stone tools in the layers in which the Denisovan human remains were located are a variant of Mousterian, with the documented use of parallel reduction strategy for the cores, and a large number of tools formed on large blades.
Decorative objects of bone, mammoth tusk and fossilized ostrich shell were recovered from the cave, as were two fragments of a stone bracelet made of a dark green chloriolite. The Denisovan levels contain the earliest use of an eyed bone needle known in Siberia to date.
- Read more about the Upper Paleolithic cultural component of Denisova Cave
Sources
This glossary entry is a part of the About.com guide to the Upper Paleolithic, and the Dictionary of Archaeology.
Derevianko AP, Shunkov MV, and Volkov PV. 2008. A Paleolithic Bracelet From Denisova Cave. Archaeology, Ethnology and Anthropology of Eurasia 34(2):13-25
Gibbons A. 2012. A crystal-clear view of an extinct girl's genome. Science 337:1028-1029.
Krause J, Fu Q, Good JM, Viola B, Shunkov MV, Derevianko AP, and Paabo S. 2010. The complete mitochondrial DNA genome of an unknown hominin from southern Siberia. Nature 464(7290):894-897.
Martinón-Torres M, Dennell R, and Bermúdez de Castro JM. 2011. The Denisova hominin need not be an out of Africa story. Journal of Human Evolution 60(2):251-255.
Mednikova MB. 2011. A proximal pedal phalanx of a Paleolithic hominin from Denisova cave, Altai. Archaeology, Ethnology and Anthropology of Eurasia 39(1):129-138.
Meyer M, Kircher M, Gansauge M-T, Li H, Racimo F, Mallick S, Schraiber JG, Jay F, Prüfer K, de Filippo C et al. 2012. A High-Coverage Genome Sequence from an Archaic Denisovan Individual. Science Express.
Reich D, Green RE, Kircher M, Krause J, Patterson N, Durand EY, Bence V, Briggs AW, Stenzel U, Johnson PLF et al. 2010. Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature 468:1053-1060.
