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Human 'sea nomads' can dive up to 13 minutes — thanks to this DNA mutation, study finds

Want to dive 200 feet underwater for up to 13 minutes at a time?

Don’t hold your breath. Unless you have this rare gene mutation — a “surprise finding” identified by scientists in a new study — chances are you can only hold your breath for seconds, or a few minutes at most. The research was published Thursday in the journal Cell.

The DNA mutation was uncovered in the Bajau people of southeast Asia, according to researchers from the University of California, Berkeley, and the Universities of Cambridge and Copenhagen. Scientists suspect the mutation alters the spleen, a part of the body that’s instrumental in maintaining body functions with limited oxygen. It’s likely that the mutation evolved over hundreds (maybe thousands) of years, scientists said.

But why is the spleen so important when it comes to diving? The organ is full of red blood cells that carry oxygen, according to researchers — so the Bajau’s huge spleens, which are 50 percent larger than average, can presumably pump more blood cells into the body as they dive. That in turn prevents the human body from becoming oxygen-starved after minutes below water, researchers said.

“The closest thing to the Bajau in terms of underwater working time is sea otters,” Melissa Ilardo, a doctoral candidate at the University of Copenhagen, said in a statement. Sea otters “are also spending about 60 percent of their time in the water.”

The group is known as “sea nomads,” given their sea-dependent traditions: The Bajau spend nearly two-thirds of their work day in the water diving to collect crustaceans and sea cucumbers or spearfish octopuses and other aquatic food at depths as far as 230 feet, researchers said.

“That is really remarkable, even compared to other professional or traditional divers,” Ilardo said. “They are just spending an extraordinarily long time underwater compared to their recovery time.”

The Bajau are spread across islands in Indonesia, Malaysia and the Philippines, researchers said. They live on boats, and almost all their food comes from the sea.

Specifically, the genetic mutation researchers found that had spread through the Bajau population “upregulates” thyroid hormone — a hormone that, in mice at least, has been linked to bigger spleens.

“Nothing is really known about the genetic basis of spleen size in humans, so it is hard to validate without further research,” Rasmus Nielsen, a professor of integrative biology at the University of California, Berkeley, said in a statement.

Researchers said the mutation the Bajau have developed is a prime example of how extensively humans can adapt to unusual environments.

Adaptations like the Bajau’s abnormally large spleens can help scientists better understand how the human body works, researcher said — and that has implications for everyone, not just the specific groups being studied.

“We can’t really ... expose people to new conditions and have controlled genetic experiments in the same way we can do in fruit flies and mice,” Nielsen said. “But nature has made experiments for us that tell us how humans react and adapt genetically to a whole new set of physiological conditions.”

The Bajau community the researchers studied was curious to learn more about their “genetic heritage” after Ilardo approached them, the study authors said.

Ilardo used a portable ultrasound machine to gauge spleen size in 59 Bajau people. To compare their spleen size to the average, she measured the spleens of 34 people in a nearby village of a different, non-diving people.

It’s possible that the Bajau’s way of life has been ongoing for more than 1,000 years, researchers said, citing linguistic analysis.

Their lifestyle goes back at least as far as 1521: That’s when a voyage led by Portuguese explorer Ferdinand Magellan — best known as the first to circumnavigate the globe — recorded coming across the seafaring Bajau.

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