doi.org/10.1093/molbev/msx206
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Scientists analyzing the genetic material of West African populations have discovered evidence that our modern human ancestors interbred tens of thousands of years ago with an extinct and previously unknown human species
This mysterious species, called by researchers the “ghost population”, contributed significantly to the DNA of many people living today in the western region of the African continent.
The study, led by Professor Sriram Sankararaman, from the University of California at Los Angeles (UCLA), was published in the journal Science Advances in February 2020.
The researchers examined the genomes of hundreds of individuals, especially the Yoruba people, from Nigeria and Benin, and Mende, from Sierra Leone.
By comparing this data with the DNA already known from Neanderthals and Denisovans, they identified genetic stretches that could not be explained solely by evolution within our own species, Homo sapiens.
These excerpts indicate that there was interbreeding between modern humans and this ghost population.
According to estimates, between 2% and 19% of the current genetic material of some West African groups comes from this extinct species.
This means that an important part of the genetic inheritance of these populations originates from a distant relative that no longer exists.
The lineage of this ghost population separated from the evolutionary line that would give rise to modern humans and Neanderthals about 650,000 years ago, possibly between 360,000 and 1 million years ago.
In other words, it divided well before the separation between our species and the Neanderthals.
The crossing itself would have happened around 43 thousand years ago, although scientists warn that there is a large margin of uncertainty in this calculation, which could vary from a few thousand to more than 100 thousand years.
Unlike what occurred outside Africa, where modern humans who migrated mixed with Neanderthals and Denisovans, this event took place entirely within the African continent, the birthplace of our species.
Homo sapiens appeared in Africa more than 300,000 years ago and, during their long stay there, they encountered and interacted with other archaic human groups that inhabited the region.
So far, there are no known fossils that can be attributed with certainty to this ghost population.
For this reason, scientists call it a “ghost”: its existence is revealed only by the marks left in the DNA of those living today.
It is not known exactly where she lived, what she looked like physically or what her final destination was – whether she was completely absorbed or whether she disappeared for other reasons.
Professor Sankararaman explained that it is still too early to say what the practical effects of this genetic mix were.
In other cases, such as Neanderthal DNA in non-African populations or a Denisovan gene that helps Tibetans live at high altitudes, there have been adaptive benefits.
In the case of West Africans, however, it is still unclear whether the genetic material from the ghost population brought any advantage or whether it had neutral or even negative impacts.
This discovery further enriches and complicates the story of human evolution.
For a long time, it was believed that crossings with other human species had occurred mainly outside Africa, after the great migration of our ancestors.
Now, it is clear that genetic history within the African continent was also marked by encounters and mixtures with archaic groups.
The study reinforces the idea that human ancestry is much more intertwined than previously imagined.
Instead of a simple, straight family tree, our history looks more like a complex web, full of unexpected branches and connections.
Modern humans carry, in their DNA, pieces of distant relatives who lived in different parts of the world and at different times.
Although the focus was on specific populations in West Africa, the researchers believe that similar signs may exist in other African groups, and new studies with more samples should help to clarify this picture better.
The lack of well-preserved fossils in Africa, due to climatic conditions that do not favor the conservation of ancient bones, makes DNA an even more valuable tool for reconstructing the past.
In short, what appeared to be just genetic variation within our species turned out to be, in fact, inherited from an ancient encounter with an unknown human cousin.
This “ghost population” is now part of our own history, present in the blood of millions of people who today call West Africa home.
The research opens new doors to understanding not only where we came from, but also how interactions between different human groups have shaped who we are today.
Published in 04/22/2026 07h02
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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