(ORDO NEWS) — A new analysis of the genomes of the most famous of ancient humans – the Neanderthals and Denisovans – has revealed an as-yet-unknown ancestor of our species – a branch of our distant ancestry without any known genome.
The study also finds additional evidence of a human-Neanderthal link – roughly 200,000 to 300,000 years ago. Thus, this crossing explains the increasingly complex history of our emergence as a species and our migration from Africa.
There is a possibility that the unknown ancestor is actually Homo erectus, an archaic human ancestor believed to have died out more than 100,000 years ago, but since no Homo erectus DNA has been found, we do not know for sure.
As shown in recent studies, a team of anthropologists used a Bayesian algorithm to deeply examine patterns in genomes – in this case, the DNA of two Neanderthals, one Denisovan and two modern Africans. The model can then correlate DNA mixing with specific time periods.
The algorithm looked for recombination events when two sets of chromosomes are mixed together, which has allowed scientists to go a long, long way in the history of crossing these species – according to the genetic markers left behind. Researchers report that about 15% of Denisovan DNA is of unknown origin.
According to the study, about 15 percent of these mysterious “super-archaic” DNA regions found in the Denisovan genome are still in circulation in humans. What ultimately happened to the extinct species remains to be seen.
Another finding from the study was that 3 to 7 percent of Neanderthal DNA is influenced by ancient H. sapiens, highlighting the number of connections that have occurred over the centuries, well before the mass migration of modern human ancestors from Africa some 50,000 years ago.
This is an exciting look at how we can learn more about past events simply by applying more advanced algorithms to the study of DNA records. It is likely that there are still many discoveries ahead regarding the life – and therefore the genetic history – of our ancestors.
Overall, given the number of gene flow events now documented among ancient hominins, it can be assumed that genetic exchange was likely whenever the two groups crossed in time and space, ”the researchers conclude in their paper.
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