It’s easy for the melodramatic sports fan to comment on how much their favorite sport has changed them. That sentiment is taken to the extreme by the Sama-Bajau islanders. These
Pacific nomads, who can be found from Indonesia to the Philippines, rely on a primarily fish diet as they spend much of their life on the water. Fishing is a bit too passive for the Sama-Bajau, who instead catch the majority of their food by diving into the sea. For years, it has been known that these nomads can routinely hold their breath for more than ten minutes at a time and can dive to depths of around 200 feet per dive without equipment. Scientists have long wondered why exactly the Sama-Bajau are able to make such superhuman feats commonplace. It now seems the answers have been hiding in their DNA this whole time.
A recent study in the Journal Cell lays out an idea that thanks to genetic mutations among the rather isolated population, the Sama-Bajau have literally evolved to become better divers. Their secret seems to lie in their spleens. When a human being enters the water, several things happen automatically in their body. Their heart will slow and their blood vessels will constrict to conserve oxygen. The spleen will also constrict, sending red blood cells into the torso which helps fortify the lungs and heart as a person ventures deeper into the water. Aquatic animals, such as seals have massive spleens relative to their other organs to specifically aid with diving.
Study author Melissa Llardo measured the spleen sizes of members of the Sama-Bajau and compared them to an Indonesian indigenous group, the Saluan, who largely live on land. The spleens of Sama-Bajau people were an average of 50 percent larger than their land-loving cousins. That’s a pretty big advantage. In bloodwork, Llardo found the Sama-Bajau carried the gene PDE10A which has been linked to spleen growth in mice.
More investigation lies ahead, but it appears that generations of Sama-Bajau pushing their bodies through freediving have led to a genetic specialization gearing them towards naturally being the best freediving talent pool in the world. Now that’s taking your sport seriously.