Homo sapiens actually descended from many populations throughout Africa

If this idea of ​​human origins in Africa goes against the most accepted theories even today, it is not entirely new.

To help confirm this theory, Professor Simon Gravel of McGill University’s Department of Human Genetics and his colleagues tested the genetic material of present-day African populations and compared them to fossils of early populations.Homo sapiens Found on the mainland.

They thus created a new model of human evolution, invalidating some previous ideas.

African continent seen from space.

Photo: Old

Different theories

According to one of these theories, a central population lived in African territory about 150,000 years ago; Other people will come from there.

Another hypothesis is that this core population was the result of interbreeding between modern humans and so-called archaic hominins, which contributed to human evolution.

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

Genetics and mathematics to the rescue

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

American anthropologist and geneticist Brenna M. from the University of California, Davis. Henn did this work.

Groups in question:

• Nama (Ko-San of South Africa);
• Mende (from Sierra Leone);
• Kumus (recent descendants of a hunter-gatherer group from Ethiopia);
• Amhara and Oromo (agrarian people of East Africa).

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

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

” We did this to question the different scenarios proposed by anthropologists, but by translating them into mathematical models we could predict what we observe in genetic diversity today. We found one that best fits the data we observe. »

A model in which there were many humans similar to each other, but isolated for hundreds of thousands of years. These populations, although isolated, exchanged genes among themselvesThe professor adds.

” Once in a while, maybe every 10,000 years, there were migrations among people, and I guess, events like climate change. »

Therefore, there would have been enough exchanges between these populations to be genetic Consistent. They will be like this Co-created.

Rather than seeing modern man appear only in one place, one can imagine that different modern features may have emerged in different parts of the continent, from North Africa, East Africa, and South Africa. They then spread over landProfessor Gravel says.

On leaving Africa

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

” This is a very complicated question. There are many releases and many combinations. »

In our model, we include European populations, but mainly assume recent, post-colonial admixture, but do not attempt to resolve what happened when they moved out of Africa 50,000 to 75,000 years ago.He says.

The teacher also wants to use the new method From an adaptive perspective, learn which mutations helped shape our genetic makeup today.

Simon Gravel also wants to refine this work on five demographics If we had a larger population, the picture of today’s genetic diversity would be more complete.

But there is still a lot of work to do to get there. More population, branches, migrations, analysis becomes more difficult! I still have a lot of work to do!