An island 80 kilometers from the southern tip of the Korean peninsula houses a unique and famous community of women: Haenyeo.
These women dive all year on the island of Jeju, collecting sea urchins, abalones and other seafood from the ocean bottom, going down until 18 meters below the surface several times over four to five hours a day. They dive during pregnancy and even old age, without the help of any breathing equipment – Just a diving outfit.
“We believe that, for thousands of years, they have been practicing this amazing matrilinear technique, learning from their mother to dive from very young. They join these groups, and that is what they do. They dive,” said Melissa Ann Ilardo, geneticist and assistant professor of biomedical computer at Utah University.
“They spend a truly extraordinary percentage of their time underwater.”
Ilardo, along with colleagues in South Korea, Denmark and the United States, wanted to understand how women can perform this amazing physical feat. Specifically, the researchers wondered if diving has a unique DNA that allows them to be without oxygen for so long or whether this capacity is the result of a life of training – or a combination of both.
The results of the investigation, published in the Scientific Journal Cell Reports On May 2, they revealed differences unique genetics that the Haenyeo They developed to deal with the physiological stress of free diving. It is a discovery that can one day lead to better treatments for blood pressure disorders, the researchers say.
“It’s a beautiful island, as they sometimes call it Hawaii da Korea. There is a coastline everywhere, rich in resources, so imagine any population living in a place like this. Of course you would like to enjoy,” said Ilardo.
Diving has been part of Jeju culture for many years. It is unclear when it has become an exclusive activity for women, but theories include a male diver tax or a shortage of men, Ilardo said. Still, the dive is so essential to the population of Jeju that the shortening of the characteristic words of the Jeju language is attributed to the need for divers to communicate rapidly, according to the new study.
However, the Practice is disappearing . Young women do not continue this matrilineal tradition; The current group of Dive Haenyeo, with an average age of around 70, can represent the last generation, the researchers observed in the study.
Diving into DNA
For the research, Ilardo and his colleagues recruited 30 Haenyeo divers, 30 women not divers of Jeju and 31 continental South Korea women. The average age of participants was 65 years. The researchers compared the heart rate, blood pressure and the size of the participants’ spleen and sequenced their genomes – a detailed genetic diagram – from blood samples.
The biggest challenge of the study was safely replicating the physical stress of being underwater for relatively long periods for participants with no diving experience, Ilardo noted. The researchers solved this problem by performing simulated dives, during which participants held their breath as they submerged their face in cold water.
“We would have loved to collect these measurements of all open -sea people, but obviously one cannot ask for women of 65 or 67, who have never dived before, who get in the water, attach breathing and dive,” said Ilardo.
“Fortunately, if you hold your breath and put your face on a bowl full of cold water, your body responds as if you are diving. And that’s because the nerve that stimulates the mimifer’s dive reflection goes through your face,” she said.
When you feel cold water combined with breathing retention, “your body says, ‘Ah, I’m diving’: so your heart rate decreases, your blood pressure increases and your spleen contracts,” she added.
The team’s analysis revealed that Jeju participants – divers and not divers – were more than four times more likely than continental Koreans of having a genetic variant associated with lower blood pressure.
“Your blood pressure increases as you dive. Their blood pressure (Jeju residents) increases less,” explained Ilardo.
Researchers believe that the characteristic may have evolved to keep babies in safe pregnancy, as the haenyeo dive during pregnancy when high blood pressure can be dangerous.
The team also found that Jeju participants were more likely to present a genetic variation that previous research associated with cold and pain tolerance. However, the researchers have not measured participants’ ability to withstand low temperatures, so they cannot say for sure whether the variant can be important to Haenyeo’s ability to dive all year round.
“Throughout winter, they dive when snowing, and until the 1980s, they did it with cotton, without any protection. There is much more than we need to explore and find answers,” said Ilardo.
Haenyeo’s dive dexterity is not only due to genetics. The study also found that diversers had slower heart rate than non -diving during testing – a factor that would help them conserve oxygen during diving.
“It was quite dramatic. In fact, their heart rate fell about 50% more throughout the dive than the control group (participants). We know it’s because of training, because it’s something we only saw in Haenyeo,” said Ilardo.
Ilardo’s previous work involving free diving communities known as Bajau in Sulawesi, Indonesia, revealed genetic adaptations that allowed the Bajau to stay for longer periods without oxygen, resulting in abnormally large battles.
However, although Jeju residents had an on average a larger spleen than participants in the study of continental South Korea, the effect was not significant when other factors such as age, height and weight were taken into consideration, she said.
A target for new medicines
The genetic variant that the study has identified in the residents of Jeju associated with lower blood pressure should be exploited deeper, according to Ben Tumble, associate professor at the School of Human Evolution and Social Change at Arizona State University.
“Those with this gene had a reduction of more than 10% in blood pressure compared to those who did not have it, a very impressive effect,” said Trumble, who did not participate in the study. “Gene coding proteins, and if we can find out which changes in proteins affect blood pressure, we can potentially create new medications.”
Almost all medical and genetic studies are conducted in industrialized populations, usually in urban centers, which makes Ilardo’s approach particularly valuable, Trumble added.
“Almost everything we know about what is ‘normal’ in terms of health comes from these sedentary urban populations. However, for 99.9% of human history, we were hunter-gatherer,” he said.
“Natural selection has optimized our bodies under selective pressures very different from those we face today.”
Ilardo said he hopes to continue studying Jeju divers and obtain a deeper understanding of medical implications.
“This study raises more questions than answers, but first of all it shows that these women are extraordinary,” she said.
“There is something biologically different from them that makes them extremely special, no matter how you characterize them, and what they do is unique and it’s worth celebrating.”
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Was this content originally published in South Korea divers evolved to live underwater? on the CNN Brazil website.
Source: CNN Brasil
Charles Grill is a tech-savvy writer with over 3 years of experience in the field. He writes on a variety of technology-related topics and has a strong focus on the latest advancements in the industry. He is connected with several online news websites and is currently contributing to a technology-focused platform.
