Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig recently announced that analysis of DNA from a tiny fragment of bone from the Denisova Cave in the Siberian Altai Mountains indicates that it may belong to a hitherto unknown hominid type.
     John Krause and colleagues managed to isolate a complete sequence of mitochondrial DNA from a fragment of finger bone found by Russian researchers in 2008 that weighed only 30mg. This was compared with 54 sequences from modern humans, an early human sequence from Kotenski, Russia, six from Neanderthals, and one each from a chimpanzee and a bonobo.  While Neanderthal mitochondrial DNA sequences have on average 202 differences from modern human sequences, the Denisova sequence has almost twice that number.
     The director of the Institute's genetics department, Svante Pääbo said "The results practically blew me away when I heard." The researchers suggest the Denisova hominid shared a common ancestor with both Neanderthals and anatomically modern humans, and may have lived alongside them as recently as 30,000 to 48,000 years ago.  In turn, this completely new mitochondrial DNA sequence might imply a fourth wave of hominin migration out of Africa.
     The researchers remain tentative in their identification of a completely new hominin species, though further research into the 'Denisova hominin' is expected to provide more detail.

Source: Spiegel Online (25 March 2010)