Scientists discovered a "hidden chapter" in human evolution

Researchers from Cambridge University have made a breakthrough in understanding human origins, discovering that the history of our species is much more complex than previously thought. According to the new study, modern humans descended not from one, but from two different ancestral populations.

Although the scientific community knows that Homo sapiens appeared in Africa approximately 300 thousand years ago, the events preceding this moment remained unclear for a long time. Now scientists have established that two ancient groups, conditionally named A and B, separated about 1.5 million years ago, possibly as a result of a large-scale migration of one of the groups to new territories.

Notably, about 300 thousand years ago, these two populations reunited, which ultimately led to the emergence of modern humans. The genetic contribution of the groups turned out to be unequal: 80% of our genetic material comes from group A and only 20% from group B.

For the study, specialists used data from the "1000 Genomes" project - a global initiative to sequence DNA from various populations across all continents. This approach allowed scientists to analyze the genetic material of modern humans rather than ancient remains, making it possible to identify traces of ancestral populations that left no physical evidence.

For decades, it was believed that Homo sapiens originated in Africa 200-300 thousand years ago from a single ancestral line. The new research does not refute the timeframe but significantly complements the picture, indicating the existence of two ancestral lines instead of one.

Interestingly, group A apparently became the ancestral population for Neanderthals and Denisovans, who appeared about 400 thousand years ago. After the reunification of groups A and B approximately 300 thousand years ago, their descendants evolved into modern humans - non-Africans, West Africans, and other indigenous African groups, including the Khoisan.

"Divergence is when a population splits into two or more genetically distinct groups, but this is not necessarily a migration event," explains the lead author of the study, Dr. Trevor Cousins.

The exact location where these evolutionary processes took place remains a subject of debate. Dr. Cousins notes that the most likely scenario is that both groups originated and developed in Africa, although there are alternative hypotheses.

"The genetic model cannot give us an exact answer, we can only make assumptions, but there are strong arguments for each scenario," says the scientist.

Researchers cannot yet confidently determine which ancient species were part of groups A and B. Fossil evidence indicates that species such as Homo erectus and Homo heidelbergensis inhabited Africa and beyond during that period, making them possible candidates.

The results of the study, published in the journal Nature Genetics, not only shed light on human origins but may also change approaches to studying the evolution of other species, including bats, dolphins, chimpanzees, and gorillas.

"Crossbreeding and genetic exchange likely played an important role in the emergence of new species in the animal world multiple times," concludes Dr. Cousins.