ABSTRACT
As far as fossil evidence goes, we know very little about Denisovans. In fact, we probably would never even have known of their existence if we
hadn’t discovered their ancient DNA. In 2007, Svante Pääbo was wrapping up his effort to decode the nuclear DNA of Neanderthal bones. He had been collaborating with Russian archeologist Anatoly Derevianko on small bones in a Siberian cave, which proved to be Neanderthal, according to mitochondrial DNA analysis. In 2009, Anatoly submitted a miniscule finger bone fragment found in another Siberian cave, namely, Denisova Cave. The mitochondrial DNA in the bone was so plentiful that Pääbo team was able to sequence the entire mitochondrial genome. The cold temperatures of the region may have kept the mtDNA in excellent condition. The test results were startling! It did not match either modern human mtDNA or Neanderthal mtDNA. It was something different from either of them. Where Neanderthal mtDNA varied from human mtDNA at 202 nucleotide locations, Denisovan mtDNA varied from ours at 385 locations. The differences in the mtDNA suggested that Denisovan man and humans had a common ancestor twice as far back in time as when we had a common ancestor with Neanderthals. In other words, our common ancestor with Denisovan man had lived about one million years ago.
