South Korea's Female Free Divers May Have Evolved to Thrive Underwater, Study Finds
South Korea’s Female Free Divers May Have Evolved to Thrive Underwater, Study Finds
The Haenyeo, a group of skilled divers on Jeju Island, plunge beneath the ocean’s surface without any breathing equipment, thanks to a combination of their training and genetics
Lillian Ali
- Staff Contributor
May 23, 2025 4:50 p.m.
A group of female South Korean free divers on Jeju Island, known as the Haenyeo, exit the water after catching marine snails in November 2015.
Chung Sung-Jun / Getty Images
On Jeju Island, 50 miles south of the Korean peninsula, senior women regularly dive up to 60 feet beneath the ocean’s surface. They collect sea urchins, sea snails called abalone and other food—and they do it all without breathing equipment.
These divers are known as the Haenyeo, or “women of the sea.” Trained from a young age, they plunge into cold ocean water year-round, throughout their lives.
“They dive throughout their whole pregnancy,” Diana Aguilar-Gómez, a geneticist at the University of California, Los Angeles, tells NPR’s Ari Daniel. She describes stories of women diving until shortly before giving birth, then returning to the water just days later.
Today, however, the practice is dwindling, and the current average age of the Haenyeo is about 70 years old. Many of the divers consider themselves to be the last of their kind.
Aguilar-Gómez and her colleagues wanted to know how the Haenyeo built their remarkable underwater resilience—and whether evolution, rather than just training, played a role in their abilities. The scientists found a variety of genetic and adaptive traits among the Haenyeo and published their work this month in the journal Cell Reports.
The research team compared 30 Haenyeo divers to 30 older non-diving women on Jeju Island, as well as to 31 older South Korean women from off the island. To keep all participants safe, they decided to conduct only “simulated dives,” where participants hold their breath and submerge their faces in a bowl of cold water. This triggers the mammalian dive reflex: The heart slows down, and the body diverts blood to the most important areas, like the brain.
“Your body says, ‘Ok, there’s not a lot of oxygen coming, let’s keep it in the organs that need it the most,’” study co-author Melissa Ann Ilardo, a geneticist at the University of Utah, tells Deutsche Welle’s Matthew Ward Agius.
The Haenyeo prepare for a dive.
Hans Hillewaert / CC BY-NC-ND 2.0
Comparing the Haenyeo to other women, researchers found that the trained divers’ heart rates fell about 50 percent more than those who weren’t divers. In an extreme case, one Haenyeo woman’s heart rate dropped by 40 beats per minute in just 15 seconds. The lowered heart rate is not genetic, though. Scientists think that any human, if they had the lifetime of training the Haenyeo do, would adapt similarly.
“We know that it’s because of training, because it’s something that we only saw in the Haenyeo,” Ilardo tells CNN’s Katie Hunt.
To look for genetic differences, researchers took saliva samples from the different groups. They found that women from Jeju, whether or not they were divers, had similar genes. Compared to non-islanders, though, researchers saw two key differences.
One has to do with cold tolerance—the Haenyeo are known for diving in frigid conditions, with surface water temperatures during their dives reaching 50 degrees Fahrenheit or colder. Ilardo tells NPR about a time she saw the Haenyeo diving in snowy weather: “They said as long as there’s not a risk that they’re going to be blown away to sea, then they still go out in the water, no matter how cold it is.”
The people from Jeju Island were more likely to carry a genetic variant that may make them more resistant to hypothermia—in previous research, it has been linked to the ability to tolerate cold temperatures and pain.
Jeju Island, known for its female free divers, seen from above.
Robert Simmons / NASA
The second difference relates to blood pressure—women from Jeju were more than four times more likely than women not from the island to have a gene variant related to lower blood pressure.
Everyone’s blood pressure increases when they dive, Ilardo tells CNN. But Jeju residents’ blood pressure increases less. This resistance to heightened blood pressure could help the Haenyeo dive while pregnant, since high blood pressure can be very dangerous during pregnancy.
The Haenyeo’s unique adaptations could hold the key to treating chronic diseases, particularly those related to high blood pressure. Gaining a better understanding of the gene tied to lower blood pressure could help scientists develop medications to protect people who are at risk of stroke or blood pressure complications, the researchers say.
Ben Trumble, an anthropologist at Arizona State University who was not involved in the study, tells theWashington Post’s Mark Johnson that this new research could give insight into how to treat cardiovascular disease.
“By working with populations like those Dr. Ilardo is working with, who aren’t sedentary office dwellers, we can gain some insights into how natural selection has helped us adapt and survive many problems that humans have faced throughout history,” Trumble says.
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#south #korea039s #female #free #diversSouth Korea's Female Free Divers May Have Evolved to Thrive Underwater, Study Finds
South Korea’s Female Free Divers May Have Evolved to Thrive Underwater, Study Finds
The Haenyeo, a group of skilled divers on Jeju Island, plunge beneath the ocean’s surface without any breathing equipment, thanks to a combination of their training and genetics
Lillian Ali
- Staff Contributor
May 23, 2025 4:50 p.m.
A group of female South Korean free divers on Jeju Island, known as the Haenyeo, exit the water after catching marine snails in November 2015.
Chung Sung-Jun / Getty Images
On Jeju Island, 50 miles south of the Korean peninsula, senior women regularly dive up to 60 feet beneath the ocean’s surface. They collect sea urchins, sea snails called abalone and other food—and they do it all without breathing equipment.
These divers are known as the Haenyeo, or “women of the sea.” Trained from a young age, they plunge into cold ocean water year-round, throughout their lives.
“They dive throughout their whole pregnancy,” Diana Aguilar-Gómez, a geneticist at the University of California, Los Angeles, tells NPR’s Ari Daniel. She describes stories of women diving until shortly before giving birth, then returning to the water just days later.
Today, however, the practice is dwindling, and the current average age of the Haenyeo is about 70 years old. Many of the divers consider themselves to be the last of their kind.
Aguilar-Gómez and her colleagues wanted to know how the Haenyeo built their remarkable underwater resilience—and whether evolution, rather than just training, played a role in their abilities. The scientists found a variety of genetic and adaptive traits among the Haenyeo and published their work this month in the journal Cell Reports.
The research team compared 30 Haenyeo divers to 30 older non-diving women on Jeju Island, as well as to 31 older South Korean women from off the island. To keep all participants safe, they decided to conduct only “simulated dives,” where participants hold their breath and submerge their faces in a bowl of cold water. This triggers the mammalian dive reflex: The heart slows down, and the body diverts blood to the most important areas, like the brain.
“Your body says, ‘Ok, there’s not a lot of oxygen coming, let’s keep it in the organs that need it the most,’” study co-author Melissa Ann Ilardo, a geneticist at the University of Utah, tells Deutsche Welle’s Matthew Ward Agius.
The Haenyeo prepare for a dive.
Hans Hillewaert / CC BY-NC-ND 2.0
Comparing the Haenyeo to other women, researchers found that the trained divers’ heart rates fell about 50 percent more than those who weren’t divers. In an extreme case, one Haenyeo woman’s heart rate dropped by 40 beats per minute in just 15 seconds. The lowered heart rate is not genetic, though. Scientists think that any human, if they had the lifetime of training the Haenyeo do, would adapt similarly.
“We know that it’s because of training, because it’s something that we only saw in the Haenyeo,” Ilardo tells CNN’s Katie Hunt.
To look for genetic differences, researchers took saliva samples from the different groups. They found that women from Jeju, whether or not they were divers, had similar genes. Compared to non-islanders, though, researchers saw two key differences.
One has to do with cold tolerance—the Haenyeo are known for diving in frigid conditions, with surface water temperatures during their dives reaching 50 degrees Fahrenheit or colder. Ilardo tells NPR about a time she saw the Haenyeo diving in snowy weather: “They said as long as there’s not a risk that they’re going to be blown away to sea, then they still go out in the water, no matter how cold it is.”
The people from Jeju Island were more likely to carry a genetic variant that may make them more resistant to hypothermia—in previous research, it has been linked to the ability to tolerate cold temperatures and pain.
Jeju Island, known for its female free divers, seen from above.
Robert Simmons / NASA
The second difference relates to blood pressure—women from Jeju were more than four times more likely than women not from the island to have a gene variant related to lower blood pressure.
Everyone’s blood pressure increases when they dive, Ilardo tells CNN. But Jeju residents’ blood pressure increases less. This resistance to heightened blood pressure could help the Haenyeo dive while pregnant, since high blood pressure can be very dangerous during pregnancy.
The Haenyeo’s unique adaptations could hold the key to treating chronic diseases, particularly those related to high blood pressure. Gaining a better understanding of the gene tied to lower blood pressure could help scientists develop medications to protect people who are at risk of stroke or blood pressure complications, the researchers say.
Ben Trumble, an anthropologist at Arizona State University who was not involved in the study, tells theWashington Post’s Mark Johnson that this new research could give insight into how to treat cardiovascular disease.
“By working with populations like those Dr. Ilardo is working with, who aren’t sedentary office dwellers, we can gain some insights into how natural selection has helped us adapt and survive many problems that humans have faced throughout history,” Trumble says.
Get the latest stories in your inbox every weekday.
#south #korea039s #female #free #divers
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