Over the past 20 years, a general view of human evolutionary genetics is Homo sapiens It first appeared in Africa about 200,000 to 300,000 years ago, and descended from a single lineage. However, a new study from the University of Cambridge shows that modern humans are the result of two groups (potentially HOMO HEIDELBERGENSIS and Homo Erectus) It branched out 1.5 million years ago and gathered at a mixed event 300,000 years ago at an 80:20% ratio.
a HOMO HEIDELBERGENSISNeanderthals and Cromagnone. Image credit: Sinc/José Antonio Peñas.
“The question of where we came from has been something that has captivated people for centuries,” said Dr. Trevor Cousins of Cambridge University.
“For a long time, it has been assumed that we evolved from a single, consecutive ancestor lineage, but the exact details of our origins are uncertain.”
“Our research shows clear indications of the origins of our evolutionary being more complex, including various groups that have developed individually over a million years, and have since returned to form modern human species,” added Richard Durbin, a professor at Cambridge University.
Previous studies have already shown that Neanderthals and Denisovans are mated, but Homo sapiens About 50,000 years ago, new research suggests that a much more important genetic mixing occurred long before these interactions were about 300,000 years ago.
Unlike Neanderthal DNA, which makes up about 2% of the genome of non-African modern humans, this ancient mixed event contributes ten times its amount and is found in all modern humans.
The team's methods rely on analysis of modern human DNA rather than extracting genetic material from ancient bones, allowing us to infer the existence of ancestral populations that otherwise left no physical traces.
The authors developed a computational algorithm called Cobraa, which models the methods that ancient populations fell apart and later integrated.
They tested the algorithm using simulated data and applied it to real human genetic data from the 1000 Genomes project, a global initiative that sequences DNA from populations in Africa, Asia, Europe and America.
Researchers were able to identify these two ancestral populations, but also identified some impressive changes that occurred after the two populations were initially decomposed.
“At the moment the two ancestral populations split, we see a serious bottleneck in one of them, suggesting that it had been reduced to a very small size before slowly growing over a million years,” said Professor Aylwyn of Cambridge University.
“This group later contributed to about 80% of modern human genetic material and also appeared to be a population of ancestors that diverged the Neanderthals and Denisovans.”
“However, some of the population genes that contributed to our small numbers of genetic material, especially those associated with brain function and neural processing, may play an important role in human evolution,” Dr. Cousins said.
This is a reconstruction of the artist Homo Erectus. Image credit: Yale University.
Scientists also found that genes inherited from the second population are often separated from the genome regions associated with gene function, suggesting that they may be less compatible with numerous genetic backgrounds.
This suggests a process known as the cleansing of selection, in which natural selection removes harmful mutations over time.
So who was our mystical human ancestors? Fossil evidence suggests species such as Homo Erectus and HOMO HEIDELBERGENSIS Although he lived in both Africa and other regions during this period, becoming a potential candidate for these ancestral populations, more research (probably more evidence) is needed to identify which genetic ancestors correspond to which fossil groups.
The authors hope to refine the model to explain more progressive genetic exchanges between populations rather than sharp divisions or reunions.
They also plan to explore how their findings relate to other anthropology discoveries, such as fossil evidence from Africa, suggesting that early humans may have been much more diverse than previously thought.
“It's amazing to see today's DNA and reconstruct events that were hundreds of thousands or millions of years ago,” Professor Scally said.
“And we can tell you that our history is much richer and more complicated than we imagined.”
study It was published in the journal today Natural Genetics.
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T. Cousins et al. The structured coalescence model reveals the deep ancestral structure shared by all modern humans. Nat GenetPublished online on March 18th, 2025. doi:10.1038/s41588-025-02117-1
Source: www.sci.news
