Mutated Tribe Develops 'Sea Nomad Gene' To Dive To Ocean's Depths

Imagine humans living most of their lives in the water—diving, fishing, and even sleeping on houseboats. That’s precisely how the Bajau people of Indonesia have lived for more than a millennium. Their daily routine isn’t a beach vacation; it’s a constant immersion in the ocean.

Now, scientists have discovered that the Bajau haven’t just trained their bodies to dive deep and stay underwater for minutes—they’ve evolved to do it. For generations, Bajau families have made their homes on stilts or houseboats along Indonesia’s coasts.

Children grow up learning to free-dive, using only a pair of simple wooden goggles and a weight belt. They plunge to impressive depths to hunt fish and collect sea cucumbers. It’s common to see them spend five, six, or even eight hours a day in the water, submerging themselves repeatedly and resting only long enough to haul in their catch.

Biologists long assumed this was purely a matter of training and lifestyle. However, a team led by Melissa Ilardo at Cambridge University has identified a genetic twist that gives the Bajau a built-in edge.

The key lies in their spleens. Normally, when a person holds their breath underwater, their spleen contracts and releases extra red blood cells into the bloodstream, boosting oxygen capacity by around nine percent. This “spleen squeeze” is part of our natural dive reflex—but in the Bajau, it’s supercharged.

"The tribe that evolved to stay underwater longer"

Ilardo’s team compared genetic samples from Bajau divers with those of a neighboring group, the Saluan, who live on land and fish from boats but don’t dive as deeply or as often. They found that the Bajau carry a specific mutation, nicknamed the “sea nomad gene,” that promotes larger spleen size.

In effect, their bodies store more oxygenated blood, allowing them to stay underwater longer and dive deeper without extensive training, which alone explains their prowess.

“There’s not a lot of information out there about human spleens in terms of physiology and genetics,” Ilardo told the BBC, “but we know that deep-diving seals, like the Weddell seal, have disproportionately large spleens. We believe that in the Bajau, they have an adaptation that increases thyroid hormone levels and therefore increases their spleen size.”

Studies in mice support this: when scientists remove the thyroid hormone T4, mice develop much smaller spleens. Then, if they inject T4 back in, the spleen size returns to normal. It’s a clear link between thyroid function and spleen growth—a link the Bajau have taken advantage of through natural selection over centuries of life at sea.

Insights on Human Adaptation

Dr. Andrew Weil, a leading expert in integrative medicine, highlights the remarkable adaptability of the human body in extreme environments. He notes that the Bajau people's ability to dive deep and hold their breath for extended periods is a fascinating example of evolutionary biology in action. This adaptation might involve physiological changes such as larger spleens, which help store more oxygen and enhance diving capabilities.

Dr. Weil emphasizes that understanding these adaptations can inspire modern medicine to explore how lifestyle and environment influence our health. He suggests integrating traditional knowledge with scientific inquiry to develop innovative health solutions.

Bajau divers can reportedly hold their breath for up to 13 minutes.

Just how long can a Bajau diver hold their breath? Some claim more than 13 minutes at a stretch. At the same time, that figure might sound like folklore. Even an eight- or nine-minute dive is far beyond what untrained people can manage. And it isn’t just about the length of time; these divers routinely reach depths of up to 230 feet, all on a single breath.

Yet the Bajau’s remarkable lifestyle is under serious threat. Their traditional way of life, moving freely between fishing grounds, means many lack formal citizenship, making it hard to access education, healthcare, or legal protection.

In addition, large-scale commercial fishing depletes the reefs they depend on, and destructive practices like blast fishing have damaged coastal ecosystems.

With fewer fish to catch, some younger Bajau are tempted to take on wage labor in towns, leaving behind the seafaring traditions that shaped their bodies and culture. At the same time, climate change is altering the coastal environments they call home, driving saltwater further inland and making freshwater scarce.

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Conservationists and anthropologists worry that if these pressures continue, we could lose more than a unique cultural heritage. We might also lose the chance to learn from the Bajau about human adaptability.

The insights from their “sea nomad gene” could one day inform treatments for conditions where oxygen delivery is critical, such as stroke, heart attack, and even high-altitude sickness.

Anthropologists emphasize the cultural significance of the Bajau's ocean lifestyle. Their deep connection to the sea showcases the importance of cultural practices in shaping human physiology. Dr. Pasi Sahlberg, an education expert, suggests that learning from indigenous practices can enhance modern educational frameworks, particularly in environmental studies.

He advocates for incorporating real-world applications of traditional knowledge into curricula, allowing students to appreciate the symbiotic relationship between culture and environment. By fostering such connections, educators can empower future generations to address modern challenges through a lens of sustainability and respect for ancestral wisdom.

The Bajau people's unique adaptations highlight the fascinating intersection of culture and biology. As seen through the insights of experts like Dr. Andrew Weil and Dr. Pasi Sahlberg, understanding these connections not only enriches our knowledge of human evolution but also offers practical avenues for integrating traditional wisdom into modern practices.

By valuing the lessons learned from such communities, we can enhance educational approaches and develop innovative health solutions that honor both scientific inquiry and cultural legacy. This holistic perspective is essential for addressing the challenges faced in our rapidly changing world.