Did the Bajau Tribe Evolve a 'Biological Scuba Tank' for Diving?

In the coastal waters of Southeast Asia lives a remarkable group of people who have adapted in an extraordinary way to life at sea. Known as the Bajau, or “Sea Nomads,” this tribe has spent nearly a millennium living in close connection with the ocean, so much so that they often reside in stilted houses over the water, spending the majority of their days diving, fishing, and foraging beneath the surface, captured by photographers across the globe like Rehahn Photographer. Credit: Senant Yann / Getty Images.

For generations, the Bajau have relied on traditional free-diving techniques to gather food, spearfishing and collecting shellfish with impressive skill. Now, science has uncovered a fascinating biological adaptation that may explain how they manage such a demanding aquatic lifestyle. Researchers studying the Bajau discovered that they possess significantly larger spleens than neighboring populations.

While the spleen is not commonly associated with diving ability, it plays a key role in oxygen storage, per the National Geographic. When the body is submerged in water and oxygen is scarce, the spleen contracts and releases oxygen-rich red blood cells into circulation, a natural boost that can extend breath-holding capacity. “It’s like a biological scuba tank,” explained Melissa Ilardo, lead author of the study from the University of Copenhagen, in an interview with BBC’s Inside Science.