Another character lost in the history of mankind.
Humans native to West Africa are descended in part from a currently extinct human species of which we were not aware. Up to now. New research carried out by scientists at the University of California, Los Angeles (USA), has reached this conclusion after the genetic analysis of four current African populations.
We do not have fossils but genetic evidence that an ancient population, similar to humans, left a genetic legacy in present-day West Africans. These extinct relatives of Homo sapiens passed on genes to the African ancestors of the modern Yoruba and Mende about 24,000 years ago or more, according to experts in the study published by Science Advances. The DNA suggests that the genetic differences are so important that the source had to be an entirely different hominin. They are a species of archaic hominids that, unlike Neanderthals and Denisovans, modern science has never found physical remains.
The genomes of the Yoruba and Mende groups contain a considerable percentage of the genetic material of this mysterious “ghost population.” The unexplained DNA found in people living in West Africa today does not match Neanderthals or Denisovans.
The method
The researchers analyzed the genomes of more than 400 people from four West African populations of the 1000 Genome Project , including the Yoruba and Mende populations. Using a computer modeling technique, they found that between 2% and 19% of their genetic ancestry was derived from an unaccounted source. Who was it?
This is where genetic introgression comes in, or in other words, the flow of genes that takes place when members of two populations mate and the resulting hybrid individuals reproduce with members of the parental populations. It is perfectly feasible that the hominin in question may be an entirely new species of early humans, whose ancestors would have separated from the human family tree earlier than the ancestors of Neanderthals and Denisovans.
Some transmitted DNA segments from this new Homo species influence survival-enhancing functions, including tumor suppression and hormonal regulation . Experts suspect that these genes spread rapidly among modern West Africans .
Background of other studies
Interestingly, this is not the first time ‘ghost’ species of unknown extinct ancestors have been found in modern DNA, but it is the first time it has been observed in modern West African DNA. The findings are supported by several studies suggesting that there have been multiple interbreeding events between archaic and modern human populations in Africa.
The authors say that we will need further analysis of African genomes across the continent before we can understand the true makeup of our ancestors. Continue the journey through our history.
Referencia: Recovering signals of ghost archaic introgression in African populations. Arun Durvasula1 and Sriram Sankararaman. Science Advances 12 Feb 2020: Vol. 6, no. 7, eaax5097 DOI: 10.1126/sciadv.aax5097
