New Study Challenges Prevailing Theories on Human Evolution and Fossil Record
A new study challenges prevailing theories about human evolution, suggesting that modern Homo sapiens evolved from multiple genetically diverse populations across Africa instead of a single ancestral population. The study, published in the journal Nature, analysed genetic data from present-day African populations, including 44 newly sequenced genomes from the Nama group of southern Africa. According to the study, the initial discernible division among ancient human groups happened around 120,000 to 135,000 years ago. This was after extended periods of genetic blending, and later movements produced a loosely organized genetic base. The authors predict that 1-4% of genetic differentiation among contemporary human populations can be attributed to variation in the stem populations. These findings also imply that contributions from archaic hominins were unlikely to have significantly affected Homo sapiens’ evolution.
The research team used a new algorithm to test hundreds of possible scenarios and found that those with gene flow back and forth between populations in various parts of the continent over the course of hundreds of thousands of years provided a much better explanation of the genetic variation seen today. The study included newly sequenced genomes from 44 members of a southern African group known as the Nama, who carry exceptional levels of genetic diversity compared to other modern groups. The scientists incorporated Eurasian genetic elements in order to account for the impact of colonial interactions and blending that occurred in Africa.
The authors concluded that if their model predicts the genetic differences between the stems were similar to those among contemporary human populations, the most morphologically divergent fossils are unlikely to represent the branches that contributed to the evolution of humans. This has important implications for the interpretation of the fossil record, as morphologically divergent hominid fossils such as Homo naledi are unlikely to represent branches that contributed to the evolution of Homo sapiens.
In addition to shedding light on human evolution, a recent study published in the journal Science also revealed how early human species adapted to mosaic landscapes and diverse food resources, which would have increased our ancestor’s resilience to past shifts in climate. The research team used a vast compilation of over 3,000 well-dated human fossil specimens and archeological sites, combined with accurate climate and vegetation model simulations covering the past three million years. Their findings suggest that earlier African groups had a preference for open environments such as grassland and dry shrubland, while hominins like H. erectus and later H. heidelbergensis and H. neanderthalensis developed higher tolerances to other biomes over time, including temperate and boreal forests. Eventually, H. sapiens emerged around 200,000 years ago in Africa, becoming the master of all trades and surviving in harsh environments such as desert and tundra.
0. “New DNA Research Changes Origin of Human Species” SciTechDaily, 18 May. 2023, https://scitechdaily.com/new-dna-research-changes-origin-of-human-species/
1. “Did Humans Originate From A Single Place In Africa? Study Rejects Old Theory, Presents New Timeline” ABP Live, 18 May. 2023, https://news.abplive.com/science/humans-originate-africa-evolve-neanderthals-stem1-stem2-new-study-unravels-secrets-rejects-old-theory-1603159
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