Researchers have identified a key genetic adaptation that enables Turkana pastoralists in northern Kenya to withstand chronic dehydration without the kidney damage typically associated with severe fluid loss.
The study, published in Science, sheds light on a survival mechanism in one of the driest inhabited regions on Earth. By analyzing 367 whole genomes, scientists detected eight DNA regions showing signs of recent natural selection, with one standing out prominently.
Through the Turkana Health and Genomics Project, teams from Kenya and the United States linked this genetic signal to the persistent stress caused by water scarcity.
The STC1 gene
The strongest signal was found in the STC1 gene, which becomes active in the kidneys during dehydration. When water intake is limited, the body conserves fluids by concentrating urine. Laboratory findings showed that the antidiuretic hormone—the signal that instructs the kidneys to retain water—activates STC1.
Because this mechanism is directly tied to survival, even a modest genetic advantage could become amplified over generations.
Diet also appears to play a significant role. Between 70% and 80% of the traditional Turkana diet consists of animal products, primarily milk, blood, and meat. These foods produce urea as a byproduct of protein metabolism, and the study links STC1 to urea regulation. This connection may explain why gout remains rare in the population despite a diet that would challenge many others.
Evolution over millennia
Researchers suggest the beneficial variant did not emerge suddenly but likely existed at low frequency before becoming advantageous as the region grew increasingly arid around 5,500 years ago. Natural selection appears to have acted over a period of 5,000 to 8,000 years.
A similar adaptation was also identified in the Daasanach people of East Africa, though it seems to have evolved independently under comparable environmental pressures. The evolutionary advantage of the variant is estimated at around 5%, placing it among the strongest known examples of recent human adaptation.
The research was preceded by years of engagement with Turkana community leaders and members, and expanded into a broader health initiative involving more than 5,000 participants. This allowed scientists to connect genetic findings not only to dehydration, but also to diet, water access, and the impacts of transitioning from pastoral to urban lifestyles.