Meat, blood, milk, and almost no water: Scientists find what helped Kenyan tribe survive on extreme diet for centuries

The Kenyan tribe of Turkana pastoralists can survive without water and only on a diet of milk, meat, and blood. Living in an extremely arid region where water is scarce, and temperatures can reach 50 degrees Celsius, this has been possible because of a mutation. Over thousands of years, their bodies have evolved to survive chronic dehydration. They eat a high-protein diet and almost no water; almost every other human would not be able to live healthily in this manner. But the Turkanas can. An international team of scientists has found that this has been possible because of evolutionary adaptations due to regional aridification that intensified 5,500 years ago. Their kidneys have changed so much that they can aggressively conserve water and process heavy loads of animal protein without causing any harm.

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Evolution led Turkanas to remain healthy on less water and more meat

“If you and I went on a Turkana diet, primarily eating lots of meat, fat and protein, we’d probably get sick very fast,” study co-author Julien Ayroles said. "But this community has been eating these foods for many generations and is adapted," he added, saying that this is what the study tried to understand. What has simply happened is that their bodies have evolved to survive in a harsh climate with very little water. US and Kenyan researchers sequenced the genomes of 367 people and analysed over seven million genetic variants. Eight distinct DNA regions showed natural selection. One gene showed the strongest signal.

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This is STC1, which is activated in the kidneys during dehydration. When the body is deprived of water, the kidneys work to concentrate urine to prevent water loss. STC1 is allowing the Turkana to concentrate the urine, Ayroles explained. STC1 has also been linked to urea levels in the body and explains how the Turkanas can process milk, blood, and meat, which forms 70-80 per cent of their diet. The gene protects the kidneys from waste products, like urea and uric acid, created by the high-meat diet. This is why the Turkanas do not suffer from gout.

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Natural selection kicked in among Turkanas

The changes in the community started occurring 5,000 to 8,000 years ago when northern Africa went dry. Natural selection led to genetic variants that led humans to survive in the harsh environment to take over, and slowly those with a mutated STC1 had more children, making it the dominant lineage. However, this adaptation had an adverse effect on the Turkanas who lived in cities because it did not match their conditions. Scientists noted that they were at a higher risk of developing diabetes, hypertension and kidney problems.