Discovery of early humans changes what we know

Our species, Homo sapiens, emerged thousands of years ago in Africa. Initially, through research on the DNA of living people, it was estimated that our early ancestors remained on the continent for a long time, with a small group leaving to explore the rest of the planet only 50,000 years ago.

Since then, scientists have been interested in trying to understand why it took our species so long to leave Africa. However, based on new studies, especially those published on Thursday (11) in SciencesWe can speculate that the pre-drawn timeline is wrong.

New data suggests that several waves of modern humans began migrating to other parts of the Earth about 250,000 years ago.

Sarah Tishkoff, a geneticist at the University of Pennsylvania (USA), said. New York times “There was not one migration out of Africa. There were many migrations out of Africa at different times.

Tishkov also said that previous migrations went unnoticed, which is why the gap was so large and somewhat unnatural. According to the researcher, they went unnoticed because people who moved earlier did not leave a clear fossil record, and modern humans did not inherit their DNA.

However, scientists are beginning to find evidence of the first wave of Homo sapiens outside Africa in Neanderthal DNA.

Homo sapiens left Africa a long time ago.

• Neanderthals are thought to have emerged in Africa about 600,000 years ago, before migrating to Europe and Asia;
• In 2010, Swedish geneticist Svante Pääbo, together with colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany), released the first draft of the Neanderthal genome;
• Reconstructed from 40,000-year-old Croatian fossils.
• They also found that living people from outside Africa carry parts of Neanderthal DNA, a sign of long-ago interbreeding;
• As you remember differenceLast May, researchers estimated which Neanderthals and modern humans briefly crossed, between 47,000 and 40,000 years ago.

But part of the Neanderthal DNA doesn’t fit this clear-cut view of the situation. For example, the Neanderthal Y chromosome looks more like the Y chromosome found in living humans than the rest of the Neanderthal genome.

In 2020, other researchers I tried to explain The reason. According to them, male Neanderthals inherited a new Y chromosome from humans between 370,000 and 100,000 years ago, however, this theory can only be proven true if a wave of Africans traveled out of their continent much earlier than previously estimated.

Recently, in the genomes of living Africans, certificate From this first wave of immigration.

Read more:

Tishkoff and colleagues compared the genome of the 122,000-year-old Neanderthal fossil with the genomes of 180 people from 12 different African populations. Previous studies have not found signs of Neanderthal DNA in African genomes.

But Tishkoff’s team found small pieces of DNA similar to those found in Neanderthals in nearly all 12 populations they studied. By examining the size and sequence of the genetic fragments they found, they concluded that Neanderthals inherited them from indigenous Africans.

So, an initial wave of Africans left the continent for Europe or Asia about 250,000 years ago and interbred with Neanderthals.

In turn, a group of researchers led by Joshua Akey, a professor of genomics at Princeton University (USA), used a different approach to analyze this issue.

After comparing the genomes of 2,000 people from around the world with three Neanderthal genomes, they ended up coming to the same conclusion as Tishkov’s team.

The report prepared by Aki and his colleagues, which was issued on Thursday (11), indicates that modern humans left Africa and interbred with Neanderthals between 200,000 and 250,000 years ago.

However, they also found evidence of another early wave of humans. When they compared the genomes of young and older Neanderthal fossils, they concluded that another group left the continent between 120,000 and 100,000 years ago.

to differenceSome of the strange human fossils found in Europe and the Middle East may belong to such waves, said paleoanthropologist Katerina Harvati of the University of Tübingen, Germany. “We are beginning to see this more complex reality in the fossil record,” said the researcher, who was not involved in the studies.

In 2019, she and her colleagues cited a 210,000-year-old Greek skull fragment that contained some features of modern human anatomy.

Aki and his team suggested that a second wave of Africans may have arrived in Israel, based on the fact that paleontologists have found fossils and modern-looking stone tools in Israeli caves dating back between 100,000 and 130,000 years ago.

The genomics professor noted that the findings suggest there were other waves of human migration that we have not yet discovered. He stressed that “this suggests that there were repeated African dispersals throughout much of human history.”

John Hawks, a paleontologist at the University of Wisconsin (USA), said: difference “There must be something different” about the peoples of the latest wave of African migration, where the initial migrations apparently failed.

For him, it is possible that African populations developed sufficient cultural knowledge to create tools, such as arrows, as well as to adapt to different places more easily than their ancestors.

Harvati, of the University of Tübingen, also casts doubt on the hypothesis that early human waves fought Neanderthals for territory and food. However, studies by Aki’s team and others suggest that Neanderthal numbers were declining at the time the last wave of humans arrived, which may have given humans an advantage.