Most people can hold their breath underwater for a few seconds. Some, for a few minutes. But a group of people known as the Bajau take free diving to the extreme. They are capable of submerging for 13 minutes at depths of 60 meters. They are humans adapted to submerge.
This nomadic people live in the waters of the Philippines, Malaysia and Indonesia. They dive to fish or in search of natural elements that can be used in crafts. A study published in the journal cell proves that a DNA mutation allows them to have larger spleens. The Bajau have a genetic advantage.
The spleen
Melissa Llardo, from the University of Copenhagen (Denmark), studied this population. She found that the average size of a Bajau’s spleen was 50 percent larger than normal. The spleen usually contracts to save oxygen. They also have a gene called PDE10A, which is thought to control a certain thyroid hormone in the Bajau. Natural selection developed this genetic advantage in the Bajau.
Cynthia Beall is an anthropologist at Case Western Reserve University (United States). She studies people who live at extreme altitudes, including the Tibetans who live “on the roof of the world.” She believes Llardo’s study opens up important research opportunities. She will do quantifiable biological tests before she is convinced that a genetic trait helps Bajau become better divers.
They not only hope to understand how the Bajau have become skilled divers. Llardo says the findings could have medical implications. The diving reflex is similar to a condition called acute hypoxia, in which humans experience a rapid loss of oxygen. The condition often causes death in emergency rooms. Studying the Bajau could serve as a new laboratory for understanding hypoxia.
Threat
But the lifestyle of sea nomads is increasingly threatened. They are considered a marginalized group. The increase in industrial fishing is also making their subsistence difficult. As a result, many choose to abandon the sea.
Without support for their way of life, Llardo worries that they will be left behind. The lessons they can provide about human health are in danger of being forgotten. But humans adapted to submerge still have a lot to teach us.
