For generations, the Bajau people of Southeast Asia have lived closely connected to the sea, earning much of their food through traditional diving. Often called the “Sea Nomads,” they can spend hours repeatedly diving underwater, sometimes reaching remarkable depths while holding their breath. For most people, staying underwater for even a few minutes is challenging, making the Bajau’s lifestyle especially fascinating. Scientists studying the community discovered that many Bajau individuals have unusually large spleens compared with nearby populations. This finding may help explain how their bodies cope with long periods underwater. The spleen stores oxygen-rich red blood cells, and during a dive, the body’s natural response slows the heartbeat and redirects oxygen toward vital organs. When the spleen contracts, it can release additional oxygenated blood into circulation, almost like a small biological oxygen reserve.

Researchers have also investigated whether genetics may contribute to this remarkable adaptation. One study identified a gene associated with spleen size and suggested that natural selection may have played a role in helping the Bajau adapt to their marine environment over many generations. Their traditional diving practices, including wooden goggles and weighted belts, have further supported their unique way of life. Importantly, scientists are not saying the Bajau possess a literal “mutant gene” that allows them to breathe underwater. Instead, their abilities appear to reflect a combination of inherited traits, physiology, culture, and generations of living around the ocean. Their story offers scientists a rare opportunity to understand how the human body can adapt to challenging environments—and it serves as a remarkable reminder of the diversity and resilience found within our species.