US and Kenyan researchers have collaborated on a study that has revealed more about genetic adaptations in people that have occurred because of environmental pressures. This effort focused on people known as the Turkana who live in north Kenya, in a hot, arid region. The work has shown how genetic changes have helped these communities to thrive in challenging conditions. The work has been reported in Science.
The Turkana people live in a vast part of northern Kenya where water is scarce and there is little shade. These communities are nomadic, and they move around one of the driest parts of the planet, in areas near Uganda, South Sudan, and Ethiopia. Turkana people often have to travel several hours to collect water, in a hot environment with little foliage or shade cover.
The study has suggested that the Turkana people are specially adapted to live in this region, and found genetic evidence of that adaptation. Most of their nutritional requirements are filled by animal products, which is common in areas where little can be grown and markets are too far away to reach.
In this study, the researchers documented the lifestyle, health, and genetic characteristics of Turkana people. They found that the vast majority - about 90% were generally healthy, if slightly dehydrated. Genetic data from these individuals revealed eight regions of DNA where natural selection has exerted pressure, and one gene in particular had particularly strong evidence.
This gene, called STC1, is typically active in the kidneys. For people who are conserving water, this gene could be helping to shield the kidneys from damage that is created during the metabolism of meat products. Those byproducts are filtered by the kidneys, and can also lead to gout. But not many Turkana seem to be affected by gout.
Changes in STC1 expression in the kidneys could also be helping Turkana people retain more water, and generate more concentrated urine.
"The Turkana have maintained their traditional way of life for thousands of years, providing us with an extraordinary window into human adaptation," said senior study author Professor Julien Ayroles of the University of California, Berkeley.
The research also found that nearby groups of people who also live in a very dry region also carry similar genetic changes.
There can also be drawbacks to these adaptations. When Turkana people settle in towns or cities, the genetic traits that helped them thrive in the desert can now become a liability. Gene expression in Turkana people who live in cities can increase their risk of chronic diseases, compared to Turkana who do not live there.
"Worldwide, Indigenous communities like the Turkana are essential partners in advancing our knowledge of human resilience," noted study co-author Dr. Dino Martins, Director of the Turkana Basin Institute. "Their experience provides lessons for how climate and environmental changes continue to shape human biology and health."
Sources: University of California Berkeley, Science