But now, a growing body of researchers has questioned this report. Working in Senegal, Cameroon, Malawi and elsewhere, they discovered evidence that early humans spread across Africa before moving elsewhere. This work has moved the field beyond the classic out-of-Africa story and is changing our understanding of how many early human groups intermingled and dispersed across the continent, providing with a clearer picture of the complex origins of our species.
Eleanor Scerri, an archaeologist at the Max Planck Institute of Geoanthropology, Jena, Germany, says: “It is becoming more and more clear that humans did not appear in one place in one part of Africa. “If we really want to understand human evolution, we need to look at the entire African continent.”
Most researchers believe that modern humans originated in Africa between 200,000 and 300,000 years ago. About 60,000 years ago, they spread to other parts of the world. However, until recently, many experts thought that these people lived in West and Central Africa, especially in the tropical forests there, only about 20,000 years ago.
For some researchers, this story was not so plausible. University of Pennsylvania geneticist Sarah Tishkoff, who has been working to unravel the deep genetic lineage of Africa for more than two decades. “They had this beautiful continent, they could travel everywhere, go to different places, with different equipment.”
The reason no one has found evidence of early human habitation in West and Central Africa, Scerri and others say, is because few people have looked there. For decades, many researchers tended to focus on the low-hanging fruit – the parts of the continent where fieldwork was most difficult. Because the climate is dry and cool in East and South Africa and the area is more open, fossils are easy to find. Much of West and Central Africa is hot and humid, so bones and DNA break down quickly. Furthermore, the area can be a difficult area to work in, not only because most of it is densely forested, but also because some areas are plagued by protracted and chaotic conflicts. .
Other studies suggest that cultural bias may also have played a role. “Most of the research was led by people from the North of the world,” says Yale University researcher Jessica Thompson. “And their attitude is, ‘We want to know how people got out of Africa, to where we came from.’
Because of all these factors, many scientists have focused on the regions of South and East Africa. This has contributed to the theory that ancient people lived in these areas. Frustrated that the academic establishment was not taking their views seriously, several researchers began to try to uncover evidence to support their views. In the last decade or so, they have found it.
Last year, a team that included scientists from Senegal, Europe and the United States reported that modern humans lived in an area along the coast of Senegal 150,000 years ago. Previous estimates placed the first human settlement in West Africa 30,000 years ago.
Furthermore, the site was in a mangrove forest, rather than the usual grasslands or open grasslands that were often associated with early human settlement. Scerri says his latest research in Senegal, which has yet to be published, could push this date even further. He says: “It is clear that in different places there were different people doing different things. “And they’ve been there for a long time. Longer than we thought. ”
Another study, from 2022, analyzed DNA from the bones of 34 people who lived in sub-Saharan Africa between 5,000 and 18,000 years ago. Examining such ancient DNA is important because it provides a clearer window into the makeup of ancient African populations. Research has shown that from 80,000 to 20,000 years ago, people who had been isolated from each other began to interact over large areas of the continent. These links were thousands of kilometers long, from Ethiopia, through the jungles of Central Africa down to South Africa.
Thompson, one of the authors of this study says: “It is clear that people were traveling all over Africa. “They didn’t live in these little isolated places.”
And a paper published four years ago in Nature examined the remains of two children found in a rock shelter in Cameroon, in western Central Africa. One of these lived 3,000 years ago, while the other lived 8,000 years ago. Researchers, from Harvard and other institutions, were able to collect DNA from two – the first ancient human DNA ever sequenced from Central Africa. They found four separate human lineages between 60,000 and 80,000 years ago, including a previously unknown lineage – which they called the “ghost member” – that probably lived in West Africa. The results provide further support for the idea that humans have been in West Africa for much longer than previously thought, and add to the evidence that human roots extend across more than one region. of Africa.
Experts say it is important to note that their closest relatives of modern humans – Neanderthals, Homo erectus and many other species – had already spread beyond Africa to Europe and Asia, in the context of who millions of years ago. But these groups contributed a very small amount of DNA to the modern human race.
Since it can be very difficult to find fossils and extract ancient DNA in many parts of Africa, scientists have had to devise new ways to find out where people lived. For example, Thompson and his colleagues studied the sediments around Lake Malawi in the northern part of the country. Over thousands of years, the lake shrank and grew, depending on the amount of rain. During the rainy season, the number of trees around the lake would increase significantly.
But Thompson found that during the rainy season that began 80,000 years ago (and continues today), the number of trees did not increase nearly as much as expected. Instead, the scientists found a lot of coal. Thompson says this shows that people lived in the area, probably in large numbers, and they burned wood on a large scale, either to change the environment for hunting or cooking or keeping warm – or three.
A central part of this new understanding is the Pan-African hypothesis: Scerri and others argue that modern humans probably came about through the intermingling of different groups from many regions of the world. the continent. “There were many modern people living in different parts of Africa,” says Scerri, “and over time we got out of complex interactions between them. “Basically , we are a combination of a combination.”
In a study published last year, the University of California at Davis geneticist Brenna Henn and her colleagues analyzed the genes of nearly 300 Africans across the continent. By analyzing and comparing genetic data, they were able to model how humans originated on the continent over the past few thousand years. They found that modern humans are descended from at least two different peoples living in different parts of the continent. He and his colleagues are now analyzing genes from 3,000 people, mostly Africans but also people of African descent living in other places, as well as Native Americans and others .
Scerri also found evidence to support the Pan-African concept. He showed that Middle Stone Age culture continued in West Africa until recently, less than 11,000 years ago. This practice, a particular method of making stone tools, disappeared earlier in other parts of the continent, 30,000 to 50,000 years ago. This is important, he says, because this is what the Pan-African theory predicts: “For example, you would expect that each region would have its own unique cultural pattern, because of the times of isolation. This research shows how this can happen. ”
Not everyone is convinced. Richard Klein, a paleoanthropologist at Stanford University who has spent decades studying the origins of modern humans and migrations in Africa, says, “I don’t understand the evolution that drives it.” the idea of where the whole of Africa originated.
Pontus Skoglund, a population geneticist at the Francis Crick Institute in London who has collaborated with Scerri, says the Pan-African view makes sense, but he is not yet fully convinced. He says: “To me, it also seems that a large part of the genealogy of modern people can be found in one place. But we don’t know. He says there is still “great uncertainty” about who was where and when.
Scerri believes more research is needed. But after years of battling skepticism, he says he feels vindicated that a new vision has arrived. He says: “Now, this is a happy place to work. “It is truly an amazing story, unfolding before our eyes.”
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