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Diving Evolution

A population of people living in Southeast Asia has long relied on diving to catch food, and researchers now report that the Bajau people have evolved larger spleens as well as genetic changes, according to Reuters. Bajau people, it adds, can dive up to 230 feet with only a facemask.

"We have examples of how humans have adapted genetically to new diets and to extreme environments," senior author Rasmus Nielsen from the University of California, Berkeley, tells Reuters. "Now we also have a new fascinating example of how humans have adapted genetically to a nomadic lifestyle on the ocean."

Nielsen and his colleagues sequenced 43 Bajau individuals and 33 Saluan individuals, a population that lives near the Bajau, but doesn't free dive. They also compared spleen sizes between the populations to confirm that Bajau people tend to have much larger spleens. When they then examined the two populations' genomes, the researchers found that while they are closely related, the Bajau harbor signals of selection near the PDE10A gene, which is involved in the regulation of smooth muscle contraction, including the muscles that surround the spleen, as they report in Cell this week.

The researchers also uncovered signs of selection in the vicinity of BDKRB2, a gene that has been implicated previously in diving response. Variants in it have been linked to increased peripheral vasoconstriction, which helps oxygenate key tissues and could allow longer dive times.