New Study Reveals Modern Humans Evolved from Two Ancient Populations, Not One

For decades, scientists believed that modern humans evolved from a single ancestral lineage in Africa. However, new research from the University of Cambridge challenges this long-held view, revealing a more intricate evolutionary history.

The study suggests that instead of coming from one group, modern humans evolved from two separate populations that split around 1.5 million years ago and later reunited approximately 300,000 years ago. This discovery reshapes our understanding of early human evolution, showing it was far less linear than previously thought.

Advanced Genetic Analysis Reveals Complex Ancestral Contributions to Human Evolution and Development

Unlike past studies that relied heavily on fossils, this research is based on advanced genetic analysis. Using a new computational model called “cobraa,” scientists analyzed full genome sequences to track ancient population splits and reunions over time. The findings show that one of these ancient groups contributed about 80 percent of modern human DNA, while the other provided around 20 percent, particularly in genes related to brain function and neural development. This genetic mixing had a lasting impact on the evolution of Homo sapiens.

The study highlights how genetic exchange played a significant role in shaping human evolution. While Neanderthal and Denisovan DNA account for only about two percent of the genome in non-African populations, this earlier interbreeding event had a much greater influence on all modern humans. Instead of evolving in a straight line, human ancestors separated, evolved independently, and later merged again, blending their genetic traits. This process contributed to the development of modern human characteristics.

Population Bottlenecks, Genetic Mixing, and Their Role in Human and Animal Evolution

Another major finding is that one of the ancestral groups experienced a severe population bottleneck, shrinking to a very small size before gradually recovering over a million years. This group eventually became the primary genetic source of modern humans and also gave rise to Neanderthals and Denisovans.

Meanwhile, the smaller genetic contributor introduced some beneficial traits, although natural selection later filtered out certain genes. These insights suggest that survival and adaptation were influenced by periods of both separation and reintegration.

Beyond human evolution, the study suggests that genetic mixing and reintegration are common in many species. By applying their methods to chimpanzees, gorillas, dolphins, and bats, researchers found similar patterns, indicating that interbreeding has been a fundamental part of evolution across different species. As genetic research advances, scientists aim to connect these genetic ancestors with fossil groups such as Homo erectus and Homo heidelbergensis, potentially rewriting the story of human origins once again.