Ancient DNA Reveals Cognitive Leap in Southern Africa – Not Driven by New Arrivals
A new study analyzing ancient DNA from individuals found at sites like the Matjes River Rock shelter in South Africa reveals a interesting story of human evolution – one where significant cognitive advancements arose within a population, rather than being brought by newcomers.
researchers examined remains spanning 10,000 to 1,500 years ago, finding consistent genetic profiles across distinct archaeological layers, each representing a unique tool-making technology. Surprisingly, despite changes in tool complexity over time, the individuals themselves showed no evidence of genetic mixing or population replacement. This contrasts sharply with patterns observed in regions like Europe, where cultural shifts often correlate with migrations.
The study identified 79 unique DNA variants present only in Homo sapiens – differences not found in Neanderthals, Denisovans, chimpanzees, or gorillas. Crucially,all modern and prehistoric Homo sapiens studied shared these variants.The genomes from Southern Africa proved especially valuable, holding a significant portion of overall human genetic variation – essentially representing half of all human genetic diversity, with the rest distributed among populations from other regions. This allows researchers to pinpoint which genetic changes were most crucial for our evolution.
While genes related to the immune system and cognitive function were identified, a surprising number of variants were linked to kidney function. Researchers hypothesize these variants may be connected to the uniquely human ability to regulate body temperature through sweating, requiring precise fluid balance control. This could have given Homo sapiens a survival advantage over Neanderthals and Denisovans.
Further analysis revealed changes in genes impacting both the immune system and neuron growth, perhaps influencing brain development and complex thought. Over 40% of the identified variants are associated with neurons and brain growth, suggesting a key role in cognitive evolution. several genes were linked to attention, hinting at a unique cognitive development in Homo sapiens.
The most significant finding is that the sophisticated thinking demonstrated in South African archaeological records – evidenced by things like decorated stone tools - appears to have originated locally around 100,000 years ago. This innovation then spread northward, carried by the genes and technologies of these local hunter-gatherers, according to archaeologist marlize Lombard of the University of Johannesburg.
