Thanks to the understanding granted to us by the fields of geneomics and evolutionary anthropology, it is becoming common knowledge that our ancestors interbred with Homo sapiens neanderthalis. Well it seems that our fore-bearers were getting it on with more then just the Neanderthals.
In Southern Siberia, at a site inside Denisova Cave, a fossil finger and tooth have given us more insight then was once thought possible. In years past, the finding of such paltry remains would garner little interest outside of the anthropological community. The fossils would be compared to others, categorized and stored. In this case, the tooth resembled those of possibly either Homo habilis or Homo erectus. There might be some light debate as to which of the two species the fossils belonged to but even this intrigue would eventually quiet.
Thankfully, we live in a time where researchers do not stop at morphology. Using techniques to extract, first mitochondrial DNA, then nuclear DNA from the finger (and later the tooth as well), Svante Pääbo, Richard Green and an international team of researchers were able to sequence the ancient nucleotides. Their results were entirely unexpected.
The DNA of these remains belonged to a new and distinct group of hominids named "Denisovans", after the cave in which the remains were unearthed. This new group of hominids were genetically and morphologically distinct from both Homo sapiens sapiens and Homo sapiens neanderthalis. This new data alone is impressive, but when the Denisovan DNA was compared to that of modern humans, yet another revelation was in store for the research team.
Upon comparison, bits of DNA similar to that of the Denisovan's were shown to be present in some modern day Melanesians. Certain Melanesians,the ethnic group now native to the island region spanning from New Guinea to Fiji and New Caledonia, were found to have as much as 4-6% of their genome in common with the Denisovan samples. Which is far more drastic than the 1-4% that modern non-Africans share with Neanderthals.
This begs the question, could their be more hitherto unknown hominid groups that our early ancestors interacted with and even interbred with? Could the stories from the Naga people of Flores, Indonesia about the Ebu Gogo be in reference to the last remaining Homo floresiensis? That their stories of generations past hunting down and killing the last of the Ebu Gogo have some precedence? But these are questions for another post...
Reich, D. et al. Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature, 2010