A South Korean feminine free diver jumps into the ocean from a ship off the coast of Jeju Island on Saturday, Jan. 15, 2022. New analysis has discovered that these ladies, generally known as Haenyeo, have particular genetic diversifications related to chilly tolerance and blood strain.
SeongJoon Cho / Bloomberg/Getty Photos
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SeongJoon Cho / Bloomberg/Getty Photos
A pair years in the past, Melissa Ilardo discovered herself aboard a motorboat traversing the ocean round Jeju Island, which sits some 50 or 60 miles off the coast of South Korea. Earlier than the vessel had even come to a cease, an older lady in a wetsuit, fins and a masks stepped into the water. Two others adopted her.
These ladies, whose plunge Ilardo captured on video, belong to an extended line of feminine freedivers on Jeju Island known as the Haenyeo.
They swam off, every with a web bag in tow to gather seafood to eat and promote. “Issues like abalone, sea urchins … seaweeds generally,” says Ilardo, an evolutionary geneticist on the College of Utah. The Haenyeo routinely dive in waters that she says are 50° Fahrenheit on the floor at finest.
“One of many first occasions I used to be there,” Ilardo remembers, “it was snowing. They mentioned so long as there’s not a threat that they are going to be blown away to sea, then they nonetheless exit within the water, regardless of how chilly it’s.”
The ladies begin diving as women and proceed nicely into outdated age, throughout all of life’s milestones. “They dive all through their entire being pregnant,” says Diana Aguilar-Gómez, a inhabitants geneticist at UCLA. “They are saying they simply dive till mainly earlier than they offer start,” and are again within the water just a few days later.
Ilardo needed to understand how the Haenyeo are able to enduring such an excessive way of life, she says: “How evolution may need formed the Haenyeo to be higher divers, to dive extra safely, to dive for longer.”
In a examine printed in Cell Stories, Ilardo, Aguilar-Gómez, and their colleagues reveal the diversifications that make the Haenyeo’s superpower attainable. It is a mixture of physiological and genetic adjustments, a few of which seem to have had an influence on the whole inhabitants of Jeju Island.
A ‘foolish’ experiment with clear outcomes
Ilardo determined to match the Haenyeo to different aged ladies on Jeju Island who aren’t divers however have an analogous genetic background, and to nonetheless others off island who aren’t associated. There have been about 30 in every group.
A Haenyeo diver swims to catch turban shells and abalones on Nov. 6, 2015.
Chung Sung-Jun/Getty Photos
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Chung Sung-Jun/Getty Photos
There was one drawback: “You’ll be able to’t take 70-year-old ladies who’ve by no means been diving and throw them within the open ocean,” says Ilardo.
Happily, there is a workaround. It is known as a simulated dive. “You maintain your breath and put your face in a bowl stuffed with chilly water,” says Ilardo, “and your physique responds as when you’re diving. Your coronary heart fee will drop measurably.”
The Haenyeo discovered the experiment just a little foolish. “They mentioned getting within the ocean, being underwater, that is diving. No matter that is, this is not diving,” remembers Ilardo. “However they nonetheless held their breath lengthy sufficient that we had been capable of elicit a response.”
That response was important: The Haenyeo coronary heart fee fell by about 50% greater than their non-diving friends. “We had one diver whose coronary heart fee dropped over 40 beats per minute in 15 seconds,” says Ilardo.
She concludes that that is traditional physiological adaptation. That is as a result of the cohort of different ladies from Jeju — the non-divers with comparable genetic make-up — did not expertise the identical drop in coronary heart fee. The distinction between the 2 teams is because of a lifetime of diving expertise.
Pushing the physique to its limits
Subsequent, the researchers took saliva samples to search for genetic variations between the completely different teams. Everybody from Jeju — each the Haenyeo and the non-divers — had mainly the identical genes, that means that the individuals of this island seem to have been genetically sculpted by generations of divers.
“What this implies is that everyone in Jeju has an equally possible likelihood of being a descendant of a diver,” says Ilardo.
Two genes stood out within the evaluation. The primary one appears to be associated to chilly tolerance. “Possibly that protects them from hypothermia in ways in which we do not absolutely perceive but,” she suggests.
The second gene was related to blood strain, possible related to blood vessel construction and performance.
“Diving will increase your blood strain,” says Aguilar-Gómez, who did this work as a PhD pupil at UC Berkeley, “and significantly by means of being pregnant that may be very harmful. It will possibly enhance your threat for preeclampsia,” and different doubtlessly life-threatening issues.
“Even when you did not die, in all probability ladies that had been protected towards this may be extra prone to have extra kids,” she says, and extra prone to go their protecting genes alongside.
As well as, Jeju Island has one of many lowest charges of stroke mortality in all of South Korea. And since stroke may end up from hypertension, Ilardo thinks the low mortality might be associated to this second protecting gene.
“Would not it’s superb if by finding out divers in Korea, we will translate these findings to develop a therapeutic that protects individuals from stroke all over the world?” says Ilardo. “By finding out these populations, it could possibly result in discoveries that might have actually Vital implications for individuals in every single place.”
Stephen Cheung research excessive physiology at Brock College in Canada and wasn’t concerned within the analysis. He says he finds the work fascinating. “By pushing the physique to its limits,” he says, “we get a greater sense of the place these limits are, but in addition simply what the human physique is able to.”
Ilardo says she and her workforce returned to Jeju to share the outcomes with the Haenyeo — whose lifestyle is dwindling — and ensure they knew the top-line conclusion.
“These ladies are extraordinary,” she says. “Their biology is superb and what they do is superb. And so I feel it is actually vital to rejoice simply how distinctive and particular these ladies are — and the way it’s modified their our bodies and the our bodies of different individuals on this island.”
