Unlocking Evolution: New Genetic Discoveries Unveil Hidden Chapters of Human History

Researchers at the University of Cambridge have made a surprising discovery about our origins. They found that modern humans share a genetic background from two ancient groups that split about 1.5 million years ago. These groups mixed together roughly 300,000 years ago, contributing 80% and 20% to our genetic makeup, respectively.

For a long time, scientists believed Homo sapiens evolved from a single line in Africa about 200,000 to 300,000 years ago. This new research, published in Nature Genetics, challenges that simple narrative.

Dr. Trevor Cousins, the study’s lead author, noted the ongoing intrigue around human ancestry. He explained that the accepted view of a single lineage doesn’t capture the complex story revealed by their research. Co-author Professor Richard Durbin emphasized that different ancient populations developed separately for a long time before merging to form modern humans.

Past studies indicated that Neanderthals and Denisovans—two extinct relatives—interbred with our species about 50,000 years ago. But this latest research suggests that significant genetic mixing occurred even earlier, contributing more to our DNA than the Neanderthal genes do today. While Neanderthals make up about 2% of the genomes of non-Africans, this ancient mixing represents 20%.

The research team utilized advanced tools to analyze modern human DNA rather than relying on ancient remains. They drew on data from the 1000 Genomes Project, which has sequenced DNA from various global populations.

An interesting finding was that one of the ancestral groups went through a major population shrinkage before slowly increasing again—this population later contributed significantly to modern humans and seems connected to the origins of Neanderthals and Denisovans. Meanwhile, genes from the other group were less common and might not have integrated as smoothly, hinting at a process called purifying selection where harmful mutations are eliminated over time.

Notably, some genes from this secondary group, particularly those influencing brain function, may have been vital in shaping human evolution.

This research isn’t just about our past. The methods used could reshape how scientists study the evolution of other species. The cobraa computational model showed patterns in the genetic structures of not just humans but other animals too, indicating that intertwining genetic histories could be more common than we thought.

The work raises questions about what it means to evolve as a species. Fossil evidence points to various human-like species like Homo erectus and Homo heidelbergensis existing in Africa at the same time, which could relate to these ancestral populations.

Looking forward, the researchers aim to refine their model to reflect gradual genetic changes rather than dramatic splits and reunions. They also hope to further explore findings from anthropology that suggest early humans were much more diverse than previously believed.

Scally expressed amazement at the ability to reconstruct ancient events purely from modern DNA. This fresh insight reveals a richer, more intricate history than we ever imagined.

For further reading, check out Nature Genetics for detailed insight into this groundbreaking study.

Reference: Trevor Cousins, Aylwyn Scally & Richard Durbin. ‘A structured coalescent model reveals deep ancestral structure shared by all modern humans.’ Nature Genetics (2025). DOI: 10.1038/s41588-025-02117-1

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Wellcome Wellcome Aylwyn Scally, Richard Durbin, Trevor Cousins Trevor Cousins, Aylwyn Scally, Richard Durbin evolution, genetics, genome, genome sequencing, Genomics, human evolution, Human Genome Project genetics, genome, Human Genome Project, Genomics, genome sequencing, evolution, human evolution Darwin College, School of the Biological Sciences, -Department of Genetics Department of Genetics, School of the Biological Sciences, Darwin College