Wednesday, 19 February, 2020

Early humans in Africa may have interbred with an unidentified ghost species

Ghost Population’ of Archaic Humans Found in Modern Day Genes of People in West Africa Scientists find evidence of 'ghost population' of ancient humans
Sandy Nunez | 14 February, 2020, 22:57

A new study suggests that an ancient population (not yet discovered in fossils) of a very human nature could leave a genetic legacy that can still be seen in some modern West Africans.

A research conducted by two biologists from the University of California, Los Angeles, has revealed that a "ghost population" of ancient humans inhabited in West Africa almost half a million years ago.

The model developed in the study further suggests that this unknown archaic human population split millions of years ago from the lineage that gave rise to modern humans, Neanderthals and Denisovans. They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led to what is called genetic "introgression".

The discoveries are not at all definitive, but as per the experts' best guesses, the 'ghost population' separated from the ancestors of Neanderthals and today's humans between 360,000 and one million years ago.

There aren't any bones or ancient DNA to prove that theory, but researchers say the evidence is in the genes of modern West Africans. Scientists are of the opinion that traces of the genes of these mysterious population can still be found in people, reported CNN.

A Professor of Human Genetics and Computer Science with the University of California, Sriram Sankararaman said interbreeding within both species may likely have occurred some 43,000 years ago with large periods of uncertainty.

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But our understanding of the relationship between ancient human ancestors within Africa, and their connection with archaic humans, is beginning to deepen. In 2014 a landmark genetic study revealed that human beings of European and Asian descent are not entirely human, as we had previously understood the term. The researchers also note that it's possible humans interbred with several waves of different hominids over thousands of years.

"They seem to have made a pretty substantial impact on the genomes of the present-day individuals we studied", Sankararaman said.

Scientists discovered web links to the Mende individuals of Sierra Leone, Yoruba in addition to Esan individuals in Nigeria, plus various other teams in western locations of The Gambia.

The researchers are now keen to delve into the ancient genes and work out what they do. This means, some percentage of the DNA in the present day West Africans seemed to have arisen in a distant branch of humans that was not Homo Sapiens. The results were surprising: between 2 and 19 percent of the genes come from an unknown group of archaic humans. But actually knowing who those ancestors were, how they interacted, and where they existed is going to take fieldwork to find their fossil and archaeological remains.

Asked what details are known about this population, Sankararaman said, "Not much at this stage". But researchers have not yet succeeded in extracting and sequencing DNA from that fossil, or from others found in Africa that are thought to be from now-extinct hominins.