A new study published in Nature Genetics reveals that the evolutionary path of modern humans is more complex than previously thought. The research suggests that ancient human ancestors split into two separate groups around 1.5 million years ago, diverging genetically and then reconnecting about 300,000 years ago.
The study used a genome sequence analysis conducted by the University of Cambridge to identify the two ancestral populations. They found that one population donated 80% of the current human genome, while the other contributed only a minority of our genetic material.
According to lead author Dr. Trevor Cousins, the discovery challenges the long-held assumption that modern humans evolved from a single continuous ancestral lineage. The study’s co-authors, Professor Richard Durbin and Professor Aylwyn Scally, believe that their research shows “that our evolutionary origins are more complex, involving different groups that developed separately for more than a million years.”
The researchers used an algorithm called Cobraa to model how ancient humans diverged into separate populations. They discovered notable differences in the two populations shortly after they split and found evidence of severe genetic bottlenecks.
One population contributed significantly to our genetic material, while the other seems to have been the ancestral population from which Neanderthals and Denisovans diverged. The study also found that the first population locked out new genes from the second population, treating them like harmful mutations.
The researchers plan to refine their model and apply it to studying evolution in other species, including human primates and even distant relatives such as bats or dolphins. They believe that the idea of species evolving in clean, distinct lineages is too simplistic and that interbreeding and genetic exchange have played a major role in the emergence of new species.
The study’s findings are significant because they illustrate how DNA can be used to reconstruct events from hundreds of thousands of years ago. The researchers hope to further investigate ancient human diversity by correlating their work with fossil evidence and other anthropological discoveries.
Source: https://thedebrief.org/ancient-genetic-discovery-challenges-single-lineage-theory-of-human-origins