Study of Ancient DNA

Study of Ancient DNA

Reveals Crucial Role of Southern Africa in Human Evolution A new study published in Nature, the largest investigation of ancient African DNA to date, shows that a group of Homo sapiens ancestors in southern Africa, south of the Limpopo River, lived in partial isolation from other African populations for hundreds of thousands of years. Based on the analysis of 28 genomes from individuals who lived between 10,200 and 150 years ago, researchers identified genetic adaptations that likely shaped Homo sapiens. Cultural changes, such as toolmaking techniques, influenced them. They carried unique Homo sapiens-specific variants, for example, in kidney function genes for improved fluid regulation and UV protection, which are absent in Neanderthals and Denisovans. Approximately 80% of this heritage is found today in San groups such as the Juǀ'hoansi and Karretjie people. Until now, many scientists assumed that Homo sapiens originated in East Africa around 300,000 years ago and later spread southward. From there, they spread across the world in several waves, beginning around 130,000 years ago via the Arabian Peninsula to Asia. This spread was not a targeted one, but rather a gradual expansion of settlements by a few kilometers per generation, driven by climate change, resource searches, and population pressure. However, this new study, led by researchers from Uppsala University and the University of Johannesburg, suggests that Homo sapiens not only existed but also evolved in southern Africa over a longer period. The analysis revealed that Stone Age populations in the region were genetically isolated for at least 200,000 years. Significant gene flow from East and West Africa can only be detected in the data from around 1,400 years ago. Many of the analyzed remains come from the Matjes River Rock Shelter on the southern coast of South Africa. The study identified 79 unique genetic variants in all the early and modern Homo sapiens examined. These variants, which are not found in other hominins or primates, influence gene function and represent a significant portion of human genetic diversity, largely preserved only in South African groups. Seven of these variants are related to kidney function and may contribute to efficient sweating and fluid balance—both important for endurance and thermoregulation. Other variants affect the immune system and brain development; over 40% are linked to neurons, attention, and complex thinking.