Bajau Tribe- The Sea Gypsies
The Bajau people inhabit the southern Philippines, Indonesia, and Malaysia, and number around one million people. They have been living on houseboats for probably thousands of years, traveling from place to place in the waterways of Southeast Asia and only visiting land on rare occasions. They are also called sea gypsies and sea nomads.
The sea provides them with everything they require for their living. Their diet includes fishes, octopuses, sea urchins, and other aquatic organisms. They speak at least ten different languages as they have many subgroups but the most common language is sinama.
What makes them special is that they dive for around eight hours a day, spending about 60 percent of their time underwater, when they dive the traditional method. It might last from 30 seconds to several minutes, but dive to depths of more than 70 meters. They used to only come ashore to trade for food or to seek refuge from storms.
Freediving to depths of over 230 feet is how they get their food. They don't have wet suits or flippers and instead rely on handcrafted wooden goggles and spearguns. To make diving simpler, they can burst their eardrums at a young age.
The research was held in the summer of 2015 by Melissa Ilardo and the team. They took permission from the tribe for examining their spleens using an ultrasound machine and found that their spleens were bigger than the average. The fist-sized spleen, located near the stomach, eliminates old cells from the circulation and works like a biological "scuba tank" during long dives.
A "selection scan" revealed 25 places in the genome where the Bajau varied considerably from the other tribes. Even after controlling for confounding factors like age, sex, and height, one location on the PDE10A gene was found to link with the Bajau's greater spleen size. Other genes that appear to have been selected in the Bajau include BDKRB2, which is involved in peripheral vasoconstriction and the diving response; FAM178B, a regulator of carbonic anhydrase, which is involved in maintaining blood pH when carbon dioxide accumulates; and another one involved in the hypoxia response. They also have genes that allow them to see underwater.
It's a fantastic example of how humans can adapt to their surroundings, and evolve genetically according to their adaptations.