You who are reading these lines are among the last representatives of the genre. Homo which, in recent times (about 50,000 years ago), included Neanderthals, but also Denisovans, and the “hobbits” of the islands of Flores (Indonesia) and Luzon in the Philippines, discovered much more recently. Can we still talk about them as species other than our own?
For a long time, the question only concerned the relations between our species, Homo sapiens, and Neanderthal. They could have lived together in the Levant and in Europe, and they could have met “pre-biblically.” Paleogeneticists initially believed that the species barrier, prohibiting fertile interbreeding, was insurmountable, following the work of Svante Paabo (Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany).
In 2006, analyzing the DNA of small cell factories, mitochondria, extracted from Neanderthal fossils, the future Nobel Prize in Medicine (2022) concluded that our cousin and our ancestors Sapiens had not been interfertile, an essential criterion for the definition of biological species proposed by Ernst Mayr (1904-2005).
But in 2010 there was a twist! The genomic analysis of the nucleus of a Neanderthal cell, which carries most of the genetic heritage, provides, on the contrary, evidence of interbreeding with Sapiens. Svante Paabo’s team shows that current non-African human populations carry, on average, 2% DNA of Neanderthal origin.
A few weeks earlier, he had described a new genome, extracted from a phalanx about 40,000 years old, found in the cave where the Denisova man was discovered, in Siberia. The Denisovans were born for science and they also crossed paths with Sapiens – Papua New Guinea populations, in particular, have inherited up to 4% of their genome. There was also interbreeding with Neanderthals: the surprising example of a young woman born to a Denisovan father and a Neanderthal mother buried in the Denisova cave, 90,000 years ago.
“Neandertality”
The fact of finding Denisovan DNA in Neanderthal genomes, and vice versa, shows that “Mixture went in both directions and mixed-race children were accepted in the populations in question”explains Stéphane Peyrègne. Postdoctoral student at the Svante Paabo Institute, presented in July, during a seminar in Mexico, the second complete genome of a Denisovan dating back to 200,000 years ago. It bears the imprint of multiple older crossings with Neanderthals, whose existence paleogenomics had not yet revealed.
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