Can you imagine diving 200 feet underwater for up to 13 minutes at a time?
Don’t hold your breath, because it’s virtually impossible, unless you’re a mutant like the Bajua people.
Don’t worry about an impending mutant vs humans war, but should the Earth ever become a “Waterworld” as described in Kevin Costner’s epic action-drama, the Bajua will have a distinct advantage over the average land lubber.
A “surprise finding” identified by scientists in a new study — shows some surprising adaptations in the “Sea Nomad” people’s physiology.. The research was published in the journal Cell.
The DNA mutation was uncovered in the Bajau people of southeast Asia, according to researchers from the University of California, Berkeley, and the Universities of Cambridge and Copenhagen. Scientists suspect the mutation alters the spleen, a part of the body that’s instrumental in maintaining body functions with limited oxygen. It’s likely that the mutation evolved over hundreds (maybe thousands) of years, scientists said.
Leaning on the Spleen
Of all the organs in your body, the spleen is perhaps not the most glamorous. You can technically live without it, but while you have it, the organ helps support your immune system and recycle red blood cells.
Previous work showed that in seals, marine mammals that spend much of their life underwater, spleens are disproportionately large. Study author Melissa Llardo from the Center for Geogenetics at the University of Copenhagen wanted to see if the same characteristic was true for diving humans. During a trip to Thailand, she heard about the sea nomads and was impressed by their legendary abilities.
“I wanted to first meet the community, and not just show up with scientific equipment and leave,” she says of her initial travels to Indonesia. “On the second visit, I brought a portable ultrasound machine and spit collection kits. We went around to different homes, and we would take images of their spleens.
“I usually had an audience,” she adds. “They were surprised I had heard of them.”
She also took data from a related group of people called Saluan, who live on the Indonesian mainland. Comparing the two samples back in Copenhagen, her team found that the median size of a Bajau person’s spleen was 50 percent bigger than the same organ in a Saluan individual.
“If there’s something going on at the genetic level, you should have a certain sized spleen. There we saw this hugely significant difference,” she says.
The researchers also stumbled across a gene called PDE10A, which is thought to control a certain thyroid hormone, in the Bajau but not the Saluan. In mice, the hormone has been linked to spleen size, and mice that are manipulated to have lower amounts of the hormone have smaller spleens.
Llardo theorizes that over time, natural selection would have helped the Bajau, who have lived in the region for a thousand years, develop the genetic advantage.
But why is the spleen so important when it comes to diving?
The organ is full of red blood cells that carry oxygen, according to researchers — so the Bajau’s huge spleens, which are 50 percent larger than average, can presumably pump more blood cells into the body as they dive. That in turn prevents the human body from becoming oxygen-starved after minutes below water, researchers said.
“The closest thing to the Bajau in terms of underwater working time is sea otters,” Melissa Ilardo, a doctoral candidate at the University of Copenhagen, said in a statement. Sea otters “are also spending about 60 percent of their time in the water.”
The group is known as “sea nomads,” given their sea-dependent traditions: The Bajau spend nearly two-thirds of their work day in the water diving to collect crustaceans and sea cucumbers or spearfish octopuses and other aquatic food at depths as far as 230 feet, researchers said.
“That is really remarkable, even compared to other professional or traditional divers,” Ilardo said. “They are just spending an extraordinarily long time underwater compared to their recovery time.”
The Bajau are spread across islands in Indonesia, Malaysia and the Philippines, researchers said. They live on boats, and almost all their food comes from the sea.
Mr Americana, Overpasses News Desk
April 20th, 2018