The Bajau Laut people of Southeast Asia seem like real-life merfolk. Diving to depths of 259 feet and hunting underwater for three minutes become necessary abilities for the subsistence life of these nomadic sea-faring fishermen living apart from our drydocked civilization. Nature has endowed them with genetic traits to thrive underwater that researchers are very interested in studying
The Bajau Laut live a life which squeezes a little more out of the human genetic supercomputer than others in order to survive. For instance, they have a significantly enlarged spleen when compared with their land-going neighbors who gave up fishing for farming in the early 20th century.
The spleen acts as a reservoir of red blood cells. This organ contracts during a dive, sending oxygen-rich blood back into oxygen-starved organs like the heart, lungs, and brain. This adaptation is observable in marine mammals such as seals.
Understanding the genetics
The enlarged spleen was present when an international team of researchers tested not only the Bajau Laut men and women, who can spend up to 60% of their working life underwater, but also community members who weren’t active divers. This suggests that the enlarged spleen is an inherited trait.
So adults are passing these traits on to their offspring, and they’re also handing down a variation in a gene which regulates a hormone called T4, produced in the thyroid gland, which was the most varied genetic trait recorded in Bajau people.
A Tibetan connection
T4 upregulates metabolic rate, increasing the amount of energy available for use in the body, thereby increasing oxygen levels. These two genetic variations, along with a few others, suit the free-diving Bajau people right down to their flippers.
There is also some interest in comparing the traits of these sea-going people with those of a 14,000 feet above sea-level people – the Tibetans. Both face a lack of oxygen, and the team thinks studying both will dramatically increase understanding human adaptation.