Denisovans, Neanderthal and Homo sapiens

Denisovans are a Homo species or Homo sapiens arcaic subespecies that has been discovered and studied recently in Central Asia..

Denisova 3's mtDNA (Denisova 3 is the best conserved fossil sample) differs from that of modern humans by 385 bases (nucleotides) out of approximately 16,500, whereas the difference between modern humans and Neanderthals is around 202 bases. In comparison, the difference between chimpanzees and modern humans is approximately 1,462 mtDNA base pairs. This suggested that Denisovan mtDNA diverged from that of modern humans and Neanderthals about 1,313,500–779,300 years ago; whereas modern human and Neanderthal mtDNA diverged 618–321,200 years ago. Krause and colleagues then concluded that Denisovans were the descendants of an earlier migration of H. erectus out of Africa, completely distinct from modern humans and Neanderthals.

However, according to the nuclear DNA (nDNA) of Denisova 3—which had an unusual degree of DNA preservation with only low-level contamination—Denisovans and Neanderthals were more closely related to each other than they were to modern humans. Using the percent distance from human–chimpanzee last common ancestor, Denisovans/Neanderthals split from modern humans about 804,000 years ago, and from each other 640,000 years ago. Using a mutation rate of 1x10⁻⁹ or 0.5x10⁻⁹ per base pair (bp) per year, the Neanderthal/Denisovan split occurred around either 236–190,000 or 473–381,000 years ago respectively.^[22] Using 1.1x10⁻⁸ per generation with a new generation every 29 years, the time is 744,000 years ago. Using 5x10⁻¹⁰ nucleotide site per year, it is 616,000 years ago. Using the latter dates, the split had likely already occurred by the time hominins spread out across Europe.^[23] H. heidelbergensis is typically considered to have been the direct ancestor of Denisovans and Neanderthals, and sometimes also modern humans. Due to the strong divergence in dental anatomy, they may have split before characteristic Neanderthal dentition evolved about 300,000 years ago.