Mythos 7 – Denisovans

 

There have been several instances of archaic human admixture with Modern-Humans through interbreeding of Modern-Humans with Neanderthals, Denisovans, and possibly other archaic humans over the course of human history.(1)Vinayak Eswarana et al. (2005) “Genomics refutes an exclusively African origin of humans” Journal of Human Evolution, Volume 49, Number 1, Pages 1–18 Neanderthal-derived DNA accounts for an estimated 1–4% of the Eurasian genome,(2)Richard E. Green et al. (2010) “A Draft Sequence of the Neandertal Genome” Science, Volume 328, Number 5979, Pages 710–722 but it is significantly absent or uncommon in the genome of most Sub-Saharan African people. In the Pacific and Southeast Asian populations, there’s an increase of Denisovan DNA. An estimated 4–6% of the Melanesian genome is derived from Denisovans.(3)Ewen Callaway (September 22, 2011) “First Aboriginal genome sequenced” Nature News

Map of Surviving Denisovan Alleles

Map of Surviving Denisovan Alleles

Denisovans also called Denisova hominins are an extinct species of archaic humans. In March 2010, scientists announced the discovery of a finger bone fragment of a juvenile female who lived about 41,000 years ago, found in the remote Denisova Cave in the Altai Mountains in Siberia, a cave which has also been inhabited by neanderthals and modern-humans.(4)Johannes Krause et al. (2010) “The complete mitochondrial DNA genome of an unknown hominin from southern Siberia” Nature, Volume 464, Number 7290, Pages 894–897 Two teeth and a toe bone belonging to different members of the same population have since been reported. Analysis of the mitochondrial DNA of the finger bone showed it to be genetically distinct from the mitochondrial DNA of neanderthals and modern-humans.(5)Alla Katsnelson (March 24, 2010) “New hominin found via mtDNA” The Scientist Subsequent study of the nuclear genome from this specimen suggests that this group shares a common origin with Neanderthals, that they ranged from Siberia to Southeast Asia, and that they lived among, and interbred with the ancestors of some present-day Modern-Humans, with about 3% to 6% of the DNA of Melanesians and Aboriginal Australians deriving from Denisovans.(6)Morten Rasmussen et al. (2011) “An Aboriginal Australian genome reveals separate human dispersals into Asia” Science, Volume 334, Number 6052, Pages 94-98 DNA discovered in Spain suggests that Denisovans at some point resided in Western Europe, where Neanderthals were previously thought to be the only inhabitants.(7)Karl Gruber (Dec 4, 2013) “Discovery of Oldest DNA Scrambles Human Origins Picture” National Geographic A comparison with the genome of a Neanderthal from the Denisova cave revealed significant local interbreeding, with local Neanderthal DNA representing 17% of the Denisovan genome, while evidence was also detected of interbreeding with another as yet unidentified archaic human lineage.(8)Elizabeth Pennisi (2013) “More Genomes from Denisova Cave Show Mixing of Early Human Groups” Science, Volume 340, Number 6134, Page 799 In 2013, mitochondrial DNA from a 400,000-year-old hominin femur bone from Spain, which had been considered as either neanderthal or Homo heidelbergensis, was found to be closer to Denisovan mitochondrial DNA than to Neanderthal mitochondrial DNA.(9)Ewen Callaway (December 5, 2013) “Hominin DNA baffles experts” Nature, Volume 504, Pages 16–17

The genetic evidence indicates that only some humans have denisovian DNA and then not much, so clearly they weren’t our primary ancestors. Neither were the neanderthals, nor Homo erectus (Homo heidelbergensis et al.), leaving us back at the same question: what did humanity evolve from?

References   [ + ]

1. Vinayak Eswarana et al. (2005) “Genomics refutes an exclusively African origin of humans” Journal of Human Evolution, Volume 49, Number 1, Pages 1–18
2. Richard E. Green et al. (2010) “A Draft Sequence of the Neandertal Genome” Science, Volume 328, Number 5979, Pages 710–722
3. Ewen Callaway (September 22, 2011) “First Aboriginal genome sequenced” Nature News
4. Johannes Krause et al. (2010) “The complete mitochondrial DNA genome of an unknown hominin from southern Siberia” Nature, Volume 464, Number 7290, Pages 894–897
5. Alla Katsnelson (March 24, 2010) “New hominin found via mtDNA” The Scientist
6. Morten Rasmussen et al. (2011) “An Aboriginal Australian genome reveals separate human dispersals into Asia” Science, Volume 334, Number 6052, Pages 94-98
7. Karl Gruber (Dec 4, 2013) “Discovery of Oldest DNA Scrambles Human Origins Picture” National Geographic
8. Elizabeth Pennisi (2013) “More Genomes from Denisova Cave Show Mixing of Early Human Groups” Science, Volume 340, Number 6134, Page 799
9. Ewen Callaway (December 5, 2013) “Hominin DNA baffles experts” Nature, Volume 504, Pages 16–17