Modern humans left Africa much earlier than previously thought

History of the origin of mankind It continues to update itself by leaps and bounds.There is a scientific opinion that modern humans appeared in Africa, although the exact time when this happened is still unknown.

Less than ten years ago The first humans were thought to have originated in the Horn of Africa.in particular, in the vicinity of the Omo River in southern Ethiopia, where in 1967 the famous paleontologist Richard Leakey discovered in the Kibish rock formation the remains of two individuals, whose recent genetic analysis dates back between 350,000 and 250,000 years.

However, in 2017, a group of paleontologists from the Max Planck Institute for Evolutionary Anthropology in Leipzig reported the discovery Fossil Record at Jebel Irhoudin Morocco, dated to 300,000 years ago, implying that the exact origins of humanity were, to put it mildly, a fuzzy matter.

Another of the greatest mysteries was that date the moment when our ancestors decided to leave the African continentUntil a few decades ago, it was assumed that a small population of modern humans migrated from Africa. about 50,000 years ago. But many years ago it was shown that reality is not as simple as it seems.

In 2019, University of Tübingen paleoanthropologist Katerina Harvati documented that the skull remains Homo sapiens found in Greece by dand about 210.00 years agoand in 2021, the team discovered hominin fossils between 100,000 and 130,000 years old that were classified as modern humans.

Could it be that instead of one there was several waves throughout history? The rest of the puzzle will be provided to us by our closest relatives.

In the Footsteps of Neanderthals

In 2010, Swedish geneticist Svante Pääbo and his team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, published the first version of a Neanderthal genome, reconstructed from 40,000-year-old fossils found in what is now Croatia.

Sequencing has revealed important clues, such as: They found that Europeans carry Neanderthal DNA.which suggested that there was close contact between the two species, which was later demonstrated in a scientific study that found that they did indeed interbreed between 50,000 and 60,000 years ago.

The surprises don’t end there. Researchers have discovered another surprising fact. The Neanderthal Y chromosome didn’t seem to fit in the genetic sequencing of our closest relatives. It was more similar to modern humans than to the rest of its kin.

There could only be one explanation for this: Neanderthals inherited this chromosome from a much earlier human lineage. between 370,000 and 100,000 years ago, something that only makes sense if it exists wave Homo sapiens who left the African continent around this time.

That’s what a team of geneticists at Princeton University have just discovered. Using artificial intelligence algorithms, they’ve documented a history of intermarriage and genetic exchange that suggests a much closer and more ancient connection between these first human groups than was thought.

“For the first time, geneticists have identified multiple waves of interbreeding between modern humans and Neanderthals” said Limin Li, a professor in the department of medical genetics and developmental biology at Nanjing Southeast University in China and a co-author of a study recently published in the journal. The science.

“This is the first time that geneticists have identified multiple waves of interbreeding between modern humans and Neanderthals.”

Genomic sequencing with artificial intelligence

The researchers used the genomes of 2,000 living people, as well as three Neanderthals and a Denisovan. a species of the genus Homo discovered in 2010 in Denisova Cave.in Siberia. They then drew a genetic map of hominid groups over the past quarter million years.

But they did not do it the old way, by directly comparing genetic sequences, but rather, they used a genetic tool called IBDmix, which uses AI-based machine learning techniques to decode the genome.

And then the first surprise happened: they discovered that even those reference groups Homo sapiens from regions very far from the territories of the Neanderthals they counted with traces of Neanderthal DNA, were probably carried south by travelling strains or their descendants.

A combined analysis of genomic sequencing and artificial intelligence has revealed another surprising fact: not one, but several waves of modern humans left the African continent. The first of them left Africa between 200,000 and 250,000 years ago.followed by another between 100,000 and 120,000 years ago, and a final one, probably the largest of all, between 50,000 and 60,000 years ago.

“Our models show that shortly after the emergence of modern humans, We migrated from Africa and returned to the continent.– explains Joshua Akey, a professor at Princeton University’s Lewis-Sigler Institute for Alternative Genomics, in a statement from the research center. This story is about variance, about what Modern humans moved and encountered Neanderthals and Denisovans. much more than we have acknowledged so far.

“Assimilation Neanderthals and humans “their spread across Eurasia would effectively increase the size of the modern human population while reducing the number of Neanderthals,” the research team writes, concluding that The effect size for the Neanderthal population was probably smaller. than previously thought, which undoubtedly had something to do with his disappearance.