For years, scientists have assumed a straightforward family tree for humans, tracing our ancestors back to a single stream. However, new research from the University of Cambridge reveals that human evolution is more complex.
According to the study, which analyzed modern human DNA, two populations separated 1.5 million years ago and reunited just 300,000 years ago. One of these populations left a stronger genetic legacy in humans than the other.
Geneticists used statistical models and real data from the 1000 Genomes Project and Human Genome Diversity Project to uncover this population structure. The results suggest that modern humans are the result of a split between two ancestral populations, which reunited around 300,000 years ago.
This discovery challenges the common tree-of-life model, which describes species as branching off from a common ancestor. However, real-world evolution often involves interbreeding and genetic exchange, making it difficult to draw clear lines between species.
The researchers found that one of these isolated populations contributed more than 80 percent of modern human genes, while another contributed only around 20 percent. Neanderthal genes are present in non-African humans, but contribute less than 2 percent to the global gene pool.
Despite this complex picture, some geneticists argue that certain genes from the minority population may have played a crucial role in human evolution.
Source: https://www.sciencealert.com/our-genes-reveal-mysterious-split-in-human-population-1-5-million-years-ago