Homo sapiens was most likely created by a number of genetically similar populations.

Posted on 22 May, 2023 by benyamin chahkandi

Summary: Researchers have discovered a novel model of human evolution that challenges the notion that a single African population gave rise to all humans by analyzing the genetic makeup of present-day communities in Africa and comparing it to the fossil evidence of those populations' earliest Homo sapiens populations.

Although it is well known that Homo sapiens began in Africa, Brenna Henn, professor of anthropology at the Genome Center at UC Davis, and the study's corresponding author, said that it is unclear how human evolution branches diverged and how humans moved across the continent.

"This uncertainty is due to limited fossil and ancient genomic data, as well as the fact that the fossil record does not always align with expectations from models built using modern DNA," the author stated. "This new study alters the theory of species origins."

Henn and Simon Gravel of McGill University co-led research that used population genome data from southern, eastern, and western Africa to examine a variety of opposing models of evolution and migration across Africa that had been put forth in the paleoanthropological and genetics literature.

The 44 modern Nama people from southern Africa, an Indigenous population noted for having very high levels of genetic variation in comparison to other modern groups, were included in the authors' study along with newly sequenced genomes. Between 2012 and 2015, researchers collected saliva samples from contemporary people going about their daily lives in their communities in order to generate genetic data.

The model predicts that after two or more slightly genetically distinct Homo populations had been mixing for hundreds of thousands of years, the earliest population split among early humans that is discernible in modern populations took place 120,000 to 135,000 years ago. People continued to move between the stem populations after the population split, resulting in a weakly structured stem. This provides a more comprehensive account of genetic variation in both individuals and groups of humans than do previous models.

Henn stated of the study, "We are presenting something that people have never even tested before." This makes major progress in anthropological science.

Tim Weaver, co-author and professor of anthropology at the University of California, Davis, noted that earlier, more complex models had suggested contributions from archaic hominins, but that this model shows otherwise. He contributed comparative research for the study and is an authority on the appearance of early human fossils.

According to the scientists' predictions, variation in the stem populations will account for 1-4% of genetic difference between modern human populations. The application of this paradigm could have significant ramifications for how the fossil record is interpreted. These numerous lineages were likely morphologically similar due to migration between them, which means morphologically different hominid fossils (such Homo naledi) are unlikely to represent branches that helped to evolve Homo sapiens, according to the authors.

Aaron Ragsdale from the University of Wisconsin, Madison; Elizabeth Atkinson from Baylor College of Medicine; and Eileen Hoal and Marlo Möller from Stellenbosch University in South Africa are also co-authors.
 

Source: www.sciencedaily.com/releases/2023/05/230517121424.htm