New DNA evidence suggests multiple populations gave rise to modern humans

Homo sapiens originated from multiple closely related populations.

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A new study published in Nature challenges the traditional view of human evolution. Researchers from UC Davis used genetic data from current African populations and compared it to existing fossil evidence. They found that modern humans may have arisen from multiple African populations rather than a single population. 

This finding has important implications for our understanding of human evolution. It suggests that human evolution was more complex than previously thought and that multiple populations may have contributed to the development of modern humans. This new understanding of human evolution can help us better understand human populations’ diversity and the genetic basis of human traits.

Brenna Henn, professor of anthropology and the Genome Center at UC Davis, corresponding research author, said, “This uncertainty is due to limited fossil and ancient genomic data and to the fact that the fossil record does not always align with expectations from models built using modern DNA, This new research changes the origin of species.”

Researchers from UC Davis and McGill University tested a range of models of human evolution and migration across Africa. They used genetic data from modern populations in southern, eastern, and western Africa, including newly sequenced genomes from 44 modern Nama individuals from southern Africa. The Nama are an Indigenous population known to have exceptional levels of genetic diversity.

The researchers found that the best model of human evolution in Africa involves multiple populations that interbred and migrated over time. This finding challenges the traditional view that modern humans arose from a single population in Africa.

The researchers found that the earliest population split among early humans occurred 120,000 to 135,000 years ago. After this split, people migrated between the different populations, creating a “weakly structured stem.” This model of human evolution explains genetic variation among individual humans and human groups better than previous models.

The researchers also found that archaic hominins did not contribute to the evolution of modern humans. This means that morphologically divergent hominid fossils, such as Homo naledi, are unlikely to represent branches that contributed to the evolution of Homo sapiens.

This study provides new insights into human evolution and has important implications for the interpretation of the fossil record. It suggests that human evolution was more complex than previously thought and that multiple populations may have contributed to the development of modern humans. This new understanding of human evolution can help us better understand human populations’ diversity and the genetic basis of human traits.

Here are some of the key findings of the study:

• The earliest population split among early humans occurred 120,000 to 135,000 years ago.

• After this split, there was still some gene flow between the different populations, which created a “weakly structured stem.”

• Archaic hominins did not contribute to the evolution of modern humans.

• This model of human evolution explains genetic variation among individual humans and human groups better than previous models.

The implications of these findings are significant. They suggest that we need to revise our models of human evolution to consider modern humans’ complex population history. This new understanding of human evolution can help us better understand human populations’ diversity and the genetic basis of human traits.

Journal Reference: 

  1. Ragsdale, A.P., Weaver, T.D., Atkinson, et al. A weakly structured stem for human origins in Africa. Nature. DOI: 10.1038/s41586-023-06055-y
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