A team of researchers led by Dr. Johannes Krause, of the Max Planck Institute for Evolutionary Anthropology in Germany, has sequenced the entire mitochondrial DNA (mtDNA) genome of an unknown hominin from Denisova Cave in southern Siberia from a fossilized pinky finger bone. The mtDNA of this individual, who likely lived around 40,000 years ago, shows almost two times as many differences to modern human mtDNA as does Neandertal mtDNA. These genetic data indicate that modern humans and Neandertals are more closely related to each other than either is to this unknown hominin, adding significantly to our knowledge of genetic diversity in early and modern humans.
Could this mtDNA be from a relict Homo heidelbergensis population that existed long after this species was thought to have gone extinct, a reconstruction of which is shown below? Or perhaps it's Homo erectus? Or a previously unknown species?