The Bajau people, an indigenous group inhabiting the waters of Southeast Asia, are widely recognized for their profound connection to the ocean. Often referred to as “sea nomads,” they have traditionally lived a seafaring life across the coastal regions of Indonesia, Malaysia, and the Philippines. Their unique lifestyle has fostered extraordinary abilities, particularly in freediving, allowing them to navigate and sustain themselves from the marine environment.
The Bajau’s Deep Dive Prowess
The Bajau exhibit remarkable capabilities in breath-holding and underwater diving. Reports indicate that some Bajau divers can hold their breath for up to 13 minutes while descending to depths of 70 meters (230 feet). These impressive feats are often achieved using only handcrafted wooden goggles and weighted lines.
Bajau individuals may spend up to five hours underwater daily, sometimes dedicating 60% of their working hours to sub-surface activities. To manage intense underwater pressure, some Bajau divers intentionally puncture their eardrums, a practice that enables deeper dives but can lead to hearing impairment.
Physiological Changes for Underwater Life
The Bajau’s diving prowess is supported by distinct physiological adaptations, including an enhanced mammalian dive reflex. This reflex, triggered when the face is submerged, slows heart rate and constricts blood vessels in the extremities. These responses redirect oxygenated blood to the brain and heart, preserving oxygen for vital organs.
A key adaptation involves the spleen, which aids oxygen delivery during dives. When holding breath underwater, the spleen contracts, releasing a reserve of oxygenated red blood cells. Bajau spleens are notably larger, approximately 50% bigger than those of non-diving populations. This enlarged spleen acts as a natural reservoir, allowing greater oxygen release and extending underwater time.
Genetic Secrets of Bajau Divers
Scientific research identifies genetic factors contributing to the Bajau’s unique diving abilities. Studies found the Bajau population exhibits a higher prevalence of a specific variant in the PDE10A gene. This variant is associated with their enlarged spleen size, suggesting a genetic basis for this physical trait.
Further analysis indicates the PDE10A gene influences thyroid hormone T4 levels, which affect spleen size. This genetic adaptation likely evolved through natural selection, favoring individuals with traits improving free-diving. Evidence also points to selection on the BDKRB2 gene, thought to affect the human diving reflex and tolerance to low oxygen.
A Culture Shaped by the Sea
The Bajau’s extraordinary diving abilities are deeply intertwined with their traditional way of life, historically centered on the sea. They sustain themselves through fishing, spearfishing, and gathering seafood like sea cucumbers and lobsters from the ocean floor. This reliance on marine resources makes freediving an integral part of their culture and identity.
Bajau children begin learning to swim and dive at a very young age, often before they can walk. This early practice hones their underwater capabilities. Many Bajau communities traditionally live on houseboats, known as lepa-lepa, or in stilt houses over shallow waters, reinforcing their constant engagement with the marine environment.