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Kevin Costner’s creepy webs and gross gills behind his ears in Waterworld may have just been (bad) science fiction, but now an Indonesian tribe who spends nearly 60% of their day in the ocean has been found to have ‘genetically adapted’ to being underwater.

Typically, as you swim deeper into the ocean an increase in water pressure causes the lung’s blood vessels to fill with excess blood, causing a rupture and, in some cases, death. Your spleen helps you recycle red blood cells but there’s only so much it can do when you’re that deep into the water.

The Bajau tribe of Indonesia, however, are not your average divers and their genetic makeup could potentially reason why some of its members are able to ‘swim to the bottom of the ocean’.

The Bajau people, also known as Sea Gypsies or Sama-Bajau, live in houseboats and spend most of their time in the ocean, so it comes as no surprise that they are great at fishing, diving and swimming. Some of the tribe say they can dive up to 70 metres using just a set of weights and a pair of wooden goggles. For context, most divers rarely dive deeper than 40 metres.

[image:infopointregionipunto/facebook] 

[image:infopointregionipunto/facebook]

Melissa A. Ilardo, from Cambridge University, says the nomadic people can “dive repeatedly for eight hours a day, spending about 60% of their time underwater”.

After studying the tribe, she discovered that they have a genetic advantage when swimming underwater, in part, because of their extra large spleens. Some of their divers claim to have been under the sea for as long as 13 minutes, all while ‘reaching the bottom of the ocean’.

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Ilardo told the BBC there’s not a lot of information out there about human spleens in terms of physiology and genetics, but we know that deep diving seals, like the Weddell seal, have disproportionately large spleens.

“We believe that in the Bajau they have an adaptation that increases thyroid hormone levels and therefore increases their spleen size.

“It’s been shown in mice that thyroid hormones and spleen size are connected. If you genetically alter mice to have an absence of the thyroid hormone T4, their spleen size is drastically reduced, but this effect is actually reversible with an injection of T4.”

The research team also discovered a gene called PDE10A, which, in mice, is linked to spleen size. Ilardo thinks that natural selection over time would have helped the Bajau divers develop the gene.

[source:ladbible]