For hundreds of years, the Bajau , known as “sea gypsies” , have lived in the sea in Southeast Asia. Natural selection adapted them to make them genetically stronger and more resistant divers. Around a million people, in Malaysia, Indonesia and the southern Philippines , live on shellfish that they collect from the bottom of the sea.
One of the report’s authors, Melissa Ilardo , a researcher at the University of Copenhagen , says “The Bajau have probably been living on boats for thousands of years, traveling from place to place in Southeast Asian waters, occasionally visiting land.” , and adds “Everything they need they get from the sea.”
Science explains this ability.
Photograph by Matthieu Paley/National Geographic
By studying their lifestyle, researchers discovered that the Bajau’s spleens are larger than most people’s
To carry out the verification, Dr. Ilardo used a portable ultrasound machine, and asked the natives to allow her to examine their spleens.
When carrying out the test, he was able to verify that all the members of the tribe (divers and non-divers) had a similar size. But it was a big surprise, when they compared those of a group of neighboring farmers, called Saluan, to see that they were 50% larger than average. In turn, they apparently also found a genetic basis to explain this difference.
Free diving and its impact on the body.
Photograph by Matthieu Paley/National Geographic
In the book Primo Viaggio Intorno al Globo Terracqueo, the Venetian explorer Antonio Pigafetta recounted in the 16th century the incredible immersion capabilities of the bajau.
Although the size of the spleen plays a major role in the ability to dive, there are other factors involved, according to what was expressed by Richard Moon, of the Duke University School of Medicine, who studies the organic response of the spleen. human body, both at extreme depth and at high altitude.
In this regard, he states that, when submerging to great depths, the blood vessels of the lungs can burst. This is due to the pressure exerted by filling up with more blood than they can handle. Therefore, training would help to avoid this effect, in addition to genetic adaptations.
That training, added to the size of the spleen, would allow them to have more oxygen in their blood, to be able to dive without tanks and without masks.
The function of the spleen.
Photograph by Matthieu Paley/National Geographic
Dr. Ilardo says about it When they dive in their traditional way, they do it several times for about eight hours a day. They can be from 30 seconds to 13 minutes approximately and they dive to depths of more than 70 meters (sic). To dive to that depth they use weighted belts and improvised wooden goggles.
He also describes the function of the spleen as follows: “The spleen is the reservoir of oxygenated red blood cells, so when it contracts it supplies more oxygen. It is like a biological diving tank (sic). Furthermore, he adds: “There is a human response that is triggered by holding your breath and going under water” (sic).
Finally he states: «The heart rate slows down, peripheral vasoconstriction occurs. That is to say, that the blood vessels contract in the extremities to preserve oxygenated blood for vital organs and the last thing is the contraction of the spleen (sic).
A threatened town
Without going into technical or academic details, these are, broadly speaking, the reasons why the Bajau can perform the underwater feats they do.
Unfortunately they are marginalized, just like the mysterious blue-eyed tribe , and do not enjoy the same rights as the inhabitants of Indonesia (the main island). In addition, they are threatened by industrial fishing, a fact that makes their subsistence difficult.
The main concern of Dr. Ilardo is that, without the support of the local authorities and without encouragement to their way of life, they are gradually lowered, leaving the sea. This could lead to the loss of a source of information for science about the adaptations that humans can undergo to change and improve the health conditions of the species.