Homo sapiens would actually come from several populations across Africa

If this concept of human origins in Africa runs counter to the most accepted theories even today, it is not entirely new.

To help confirm this theory, Professor Simon Gravelle of the Department of Human Genetics at McGill University and colleagues tested the genetic material of current African populations and compared it to fossils of early populations.Homo sapiens Found on the mainland.

Thus they created a new paradigm of human evolution, and invalidated some of the previous ideas.

various theories

According to one of these theories, a single Central population lived on African soil about 150 thousand years ago; Other residents will come from there.

Another hypothesis is that this central group is the result of the interbreeding of modern humans and so-called ancient hominins, which contributed to human evolution.

What is interesting about our work is that it makes it possible to reconcile genetic models with paleoarchaeological and anthropological models, since human remains and tools have been found almost everywhere in Africa.says Simon Gravel, who recalls the involvement of his former student Aaron Ragsdale, now at the University of Wisconsin-Madison, in this work published in the journal nature (A new window) (in English).

Genetics and math to the rescue

In an analysis comparing different anthropological models and genetic data, the team used contemporary genomic material from 290 individuals from four groups and geographically and genetically diverse Neanderthals to identify similarities and differences between populations over the past million years. This work provided insights into genetic relationships and human evolution on the African continent.

This part of the work was done by American anthropologist and geneticist Brenna M. Henn of the University of California, Davis.

The groups involved were:

• Nama (Kho San South Africa);
• Mindy (from Sierra Leone);
• Gumuz (newly descended from a group of hunter-gatherers from Ethiopia);
• Amhara and Oromo (farming peoples of East Africa).

In addition, the research team used genetic material from Eurasian populations to track colonial raids and interbreeding in Africa.

The researchers then combined the data from these different populations with mathematical models developed by Simon Gravelle and his colleagues. And so the team used a new algorithm to quickly test hundreds of possibilities and better understand the ancient structure of the population.

” What we have done is question the various scenarios proposed by anthropologists, but translate them into mathematical models that make it possible to predict what we observe in genetic diversity today. Then we find the one that best fits the data we’re observing. »

The most stable model is the one in which there are many human groups similar to each other, but isolated for hundreds of thousands of years. These populations, though isolated, exchanged genes among themselvesadds prof.

” Occasionally, perhaps every 10,000 years, there have been population migrations and, I would expect, events such as climate change. »

Thus, there were enough exchanges between these populations for them to survive genetically Fixed. And so they will have Participate in the evolution.

Rather than seeing modern humans appearing in only one place, one can imagine that different modern aspects may have emerged in different regions of the continent, in North Africa, East Africa, and Africa to the south, for example. Then they spread to the mainlandsays Professor Gravel.

when leaving Africa

In these works, the researchers did not really attack migrationsHomo sapiens outside the African continent. Professor Gravel says future work could focus on the question, which is not without presenting difficulties.

” It’s a very complicated question. There have been many versions and many mixes. »

In our model, we include European populations, but mainly to take recent postcolonial hybridization, but not to try to solve what happened 50,000 to 75,000 years ago, when they got out of AfricaHe says.

The teacher also wants to use the new method To learn about the mutations that helped shape our genetic make-up today from an adaptive perspective.

Simon Gravel would also like to improve on this work which has been carried out on the basis of five groups, since then The larger our population, the more complete the whole picture of genetic diversity today.

But there is still a lot of work to be done to get there. More populations, branches and migrations, it becomes much more difficult to analyze! I still have a lot of work to do!