Available DNA evidence suggests that humans arose as a result of the interaction of many populations living on the continent. A new study published in Nature challenges dominant theories by suggesting that Homo sapiens evolved from many different populations in Africa, suggesting that the earliest detectable split occurred between 120,000 and 135,000 years ago, after long periods of genetic mixing.

There is general agreement that homo sapiens It comes from Africa. But there are many uncertainties and competing theories about where, when and how.

In an article published in the journal May 17, 2023 Nature An international research team led by McGill University and the University of California, Davis, suggests that humans lived in different parts of Africa, based on modern genomic data from around the continent. , migrating from one region to another and mixing with each other for hundreds of thousands of years. This view contradicts some of the dominant theories about the origin of man in Africa.

Competing theories about the origin of man in Africa

One theory states that there was a single central ancestral population in Africa about 150,000 years ago from which other populations diverged. Another proposes that this central ancestral population was the result of modern humans mixing with Neanderthal-like hominids (human-like creatures), leading to a leap forward in human evolution thought to have taken place in Eurasia.

“At different times, people accepting the single-origin classical model homo sapiens, Brenna Henn, a population geneticist in the Department of Anthropology and Genome Center at the University of California at Davis and co-author of the study, suggested that humans first appeared in East or Southern Africa. But reconciling these theories with the limited fossil record and archaeological evidence of human settlements from places as far away as Morocco, Ethiopia, and South Africa, showing that Homo sapiens can be found all over the continent, has been difficult. More at least 300,000 years ago.”

Available genomic data suggest otherwise.

In the first systematic test of these competing anthropological models on genetic data, the team worked back from modern genomic material of 290 individuals from four geographically and genetically diverse African groups, tracking similarities and differences between populations over the past millions of years and gaining insight. Genetic relationships, relationships and human evolution across the continent.

Groups Nama (Hoe-San from South Africa); Mende (from Sierra Leone); Humuses (new descendants of a group of hunter-gatherers from Ethiopia); as well as Amhara and Oromo (farmers from East Africa). The researchers also included some Eurasian genetic material to include traces of colonial invasions and mixing in Africa.

“We used a new algorithm to quickly test hundreds of possible scenarios. “The fact that genes have been exchanged over hundreds of thousands of years between populations in different parts of the continent provided a much better explanation for the genetic diversity we see today,” adds Simon Gravel, Associate Professor of Human Genetics. He is at McGill University and co-author of the paper. “We wrote this algorithm to understand how genetic disease risk varies in different populations, which prompted us to dive deep into human origins. It was very interesting to combine applied and fundamental research in this way.”