So are we all of us really “out of Africa”?
Well, mostly. Somewhere in the region of 92.5%:
Scientists are trying to envision the ancient couplings and their consequences: when and where they took place, how they happened, how many produced offspring and what effect the archaic genes have on humans today.
Other scientists are trying to learn more about the Denisovans: who they were, where they lived and how they became extinct.
A revolutionary increase in the speed and a decline in the cost of gene-sequencing technology have enabled scientists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, to map the genomes of both the Neanderthals and the Denisovans.
Comparing genomes, scientists concluded that today’s humans outside Africa carry an average of 2.5 percent Neanderthal DNA, and that people from parts of Oceania also carry about 5 percent Denisovan DNA. A study published in November found that Southeast Asians carry about 1 percent Denisovan DNA in addition to their Neanderthal genes. It is unclear whether Denisovans and Neanderthals also interbred.
The DNA sequencing that led to the discovery of other human progenitors was performed using a pinky bone and molar from a Siberian cave, and this newly discovered strain of humanity died out around 30,000 years ago. The interbreeding between modern humans, Neanderthals and Denisovans is thought not to have been, strictly speaking, consensual, but it did confer important DNA-based defenses against diseases, as witnessed by the persistence of those DNA strand over the millenia.