Homo sapiens probably arose from multiple closely related populations – ScienceDaily

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Although it is widely understood that Homo sapiens originated in Africa, uncertainty surrounds how the branches of human evolution diverged and how people migrated across the continent, said Brenna Henn, a professor of anthropology and the UC Davis Genome Center, corresponding author of the research.

“This uncertainty is due to limited fossil and ancient genomic data, and the fact that the fossil record does not always align with the expectations of models built with modern DNA,” he said. “This new research changes the origin of species.”

The research co-led by Henn and Simon Gravel of McGill University tested a variety of competing models of evolution and migration in Africa proposed in the paleoanthropological and genetics literature, incorporating population genome data from southern, eastern, and western Africa.

The authors included newly sequenced genomes of 44 modern Nama individuals from southern Africa, an indigenous population known to have exceptional levels of genetic diversity compared to other modern groups. The researchers generated genetic data by collecting saliva samples from modern individuals going about their daily activities in their villages between 2012 and 2015.

The model suggests that the first population split among early humans that is detectable in contemporary populations occurred 120,000 to 135,000 years ago, after two or more weakly differentiated genetics. Homo the populations had been mixing for hundreds of thousands of years. After the population split, people continued to migrate between stem populations, creating a loosely structured stem. This offers a better explanation of genetic variation between individual humans and human groups than previous models, the authors suggest.

“We’re introducing something that people have never tried before,” Henn said of the research. “This advances anthropological science significantly.”

“Previous, more complicated models proposed contributions from archaic hominins, but this model indicates otherwise,” said co-author Tim Weaver, a UC Davis professor of anthropology. He has experience with what early human fossils looked like and provided comparative research for the study.

The authors predict that, based on this model, between 1% and 4% of genetic differentiation between contemporary human populations can be attributed to variation in parent populations. This model may have important consequences for the interpretation of the fossil record. Due to migration between branches, these multiple lineages were likely morphologically similar, meaning morphologically divergent hominin fossils (such as homo naledi) are unlikely to represent branches that contributed to the evolution of Homo sapiensthe authors said.

Other coauthors include Aaron Ragsdale, University of Wisconsin, Madison; Elizabeth Atkinson, Baylor College of Medicine; and Eileen Hoal and Marlo Möller, University of Stellenbosch, South Africa.