This Asian Tribe Developed a Genetic Adaptation That Helps Them Stay Underwater for Hours
Across Asia and the Pacific, coastal communities have built daily life around the ocean for centuries. One of the most closely studied examples is the Bajau, a seafaring group in Indonesia whose traditional fishing culture includes repeated deep freedives. In 2018, researchers reported a genetic adaptation in the Bajau that helps explain how some divers stay underwater far longer than most people.
Researchers identified a spleen-linked adaptation in the Bajau
A study published April 19, 2018, in Cell reported that the Bajau have significantly larger spleens than a nearby non-diving population, according to the research team led by Melissa Ilardo of the University of Copenhagen. The researchers measured 43 Bajau individuals and 33 members of the neighboring Saluan population in Indonesia. They found the Bajau spleen was about 50 percent larger on average.
The study also identified a genetic variant in PDE10A that the researchers said appears linked to thyroid hormone levels and spleen size. In humans, the spleen contracts during a dive and releases oxygen-rich red blood cells into circulation. The authors stated that a larger spleen can support the body’s diving response during breath-hold activity.
The finding centered on Indonesia’s traditional sea-diving communities
The research focused on Bajau communities in Indonesia, where traditional fishing has long involved hand-diving and underwater foraging. The study described Bajau divers who can descend to around 70 meters and spend much of the workday in the water, using minimal equipment. That local setting mattered because the comparison group came from the same broader region.
What remains less certain is how broadly the finding applies across all Bajau communities in Southeast Asia. The researchers studied a limited sample in Indonesia and did not release evidence covering every Bajau population in Malaysia or the Philippines. The published paper confirmed the adaptation in the group studied, but not as a universal result for every Bajau settlement.
The study points to natural selection tied to a marine lifestyle
The authors said the most likely explanation is natural selection shaped by a long history of diving-based subsistence. Their paper stated that people with traits supporting the human dive response may have been better suited to repeated underwater hunting and gathering over many generations. The study compared the Bajau with a geographically close population to separate lifestyle from ancestry as much as possible.
For travelers and readers interested in maritime cultures, the finding adds scientific context to a community already known for exceptional freediving skill. It does not mean Bajau divers are underwater for literal hours in one breath, and the 2018 paper did not state that. What the research did confirm is a measurable biological difference tied to a traditional way of life in Indonesia.
