The BAJAUs are a tribe living mainly on the Zamboanga Peninsula and the Joló Archipelago, located in the southwestern Philippines. BAJAU is said to withstand up to 13 minutes underwater at depths between 60 and 70 meters.

Most “normal” humans hold their breath underwater for 2-3 minutes, but for Bajau, 3 minutes is practically nothing.

The BAJAU are a tribe that has a strange mutation that allows them to swim freely in sea depths that reach 60 and 70 meters for an extended period of 13 minutes; This ability allowed them to develop larger blood spleens. This is according to a study published in the scientific journal Cell which had the collaboration of scientists from the University of Copenhagen, California, and staff from the University of Cambridge. The Bajau are popularly known by the nickname of “nomads of the sea”, who for more than a thousand years traveled the coasts of Southeast Asia in Palafitos (“houses built on stilts and on the surface of the water”), always feeding on resources provided by the sea through spear hunting.

Since they never engage in this activity as a form of competition, the maximum endurance they can achieve underwater is completely unknown; a member of the tribe assured investigator Melissa Ilardo that he was able to dive for 13 consecutive minutes. Ilardo told The Atlantic that he dived with Pai Bayubu, an island member who showed him how easy it is to go down into the ocean.

But how is it possible that they can immerse themselves in the water for so long?

When you hold your breath, your body automatically activates a cardiovascular response: your heart rate slows down, while your blood vessels and spleen constrict. This protection mechanism is intended to help save energy while a limited amount of oxygen is available. In the past, it was speculated that the spleen could play an important role in allowing humans to freely immerse themselves in water for extended periods of time. However, the relationship between spleen size and diving ability has never been studied from a genetic perspective.There is now evidence that a genetic adaptation has occurred in some humans, who possess diving skills superior to those of the average man.

After a couple of visits to the site, Ilardo scanned the bodies of 59 BAJAUS with an ultrasound machine, finding that their “spleens” were 50% larger than the SULAN, a neighboring tribe that has no aquatic life

When the spleen contracts, there is an expulsion of red blood cells into the bloodstream which promotes an increase in oxygen levels. Some studies estimate that this reaction increases oxygen levels by up to 9%, thus extending the time we can stay immersed in water. This genetic adaptation favors an increase in the levels of this thyroid hormone which, consequently, results in an increase in the size of the spleen. In research with laboratory mice, the hormone thyroxine was removed through a genetic alteration, resulting in a reduction in the size of the spleen.

This is the first time that a genetic adaptation to diving has been identified in humans.

Susan Asked question April 9, 2022