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Genetics

Mutation that facilitated adaptation to a fatty diet is found in Native Americans

Léo Ramos Chaves Alteration of a gene linked to the metabolism of polyunsaturated fats is thought to have occurred 18,000 years agoLéo Ramos Chaves

A major adaptive event is thought to have occurred about 18,000 years ago among the first group of humans who had just migrated from Asia toward the Americas and found themselves in Beringia, a vast stretch of dry land that then connected Siberia and Alaska. During their stay on the natural bridge between the two continents—now mostly submerged beneath the Bering Strait—this primitive group of hunter-gatherers likely suffered the pressures of natural selection due to the extreme cold and their adopted diet, which was rich in proteins and fats. That new reality may have led to changes in their genome. One molecular marker caused by the adaptive process was likely the appearance of a mutation in a gene of the FADS family, linked to the metabolism of polyunsaturated fats such as Omega-3. An international study in 2015 found that mutation—which enhances digestion of foods rich in fatty acids—only in the DNA of the present-day Inuit populations of Greenland. A new study by a team of Brazilian researchers has identified that genetic variant in the DNA of 53 Native Americans groups currently living in North and South America (PNAS, February 13, 2017). “The Inuits are only one of the populations that carry the signs of natural selection in this gene,” explains geneticist Tábita Hünemeier of the Biosciences Institute at the University of São Paulo (IB-USP), one of the study’s authors. The new analysis also indicates that the mutation occurred during the time this population group was in Beringia and had not yet expanded throughout the Americas.

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