years ago, Melissa Ilardo Find yourself riding on a motorboat through the ocean near Jeju Island, about 50 or 60 miles from the coast of South Korea. Before the boat even stopped, an old woman in a wetsuit, fins and mask gradually fell into the water. The other two followed her.

The plunge of these women Ilardo The women captured in the video belong to a group of female Liberty named Haenyeo on Jeju Island.

They wandered, each with a drag-in clean bag to collect seafood for food and for sale. "Sometimes abalone, sea urchin...seaweed sometimes," said Elardo, an evolutionary geneticist at the University of Utah. "Hayeyeo, she said, often dives in waters, at most 50° Fahrenheit.

Iraldo recalled: “The first time I was there.

Women begin diving as girls and continue to grow old, a milestone throughout their lives. “They dive throughout their pregnancy.” Diana Aguilar-Gómeza population geneticist at UCLA. "They said they were just diving until basically before they were born." A few days later, they returned to the water.

Irado wondered how Heinho could tolerate this extreme lifestyle, she said: “How evolution has allowed Hayeo to shape a better diver, dive safer, and dive longer.”

In a published study Cell ReportsIlardo, Aguilar-Gómez and colleagues reveal the adaptation that made Haenyeo's superpower possible. It's a mixture of physiological and genetic changes, some of which seem to have an impact on the entire population of Jeju.

A "stupid" experiment with clear results

Ilardo decided to compare Haenyeo with other older women on Jeju Island who are not divers but have similar genetic backgrounds, as well as other women who have no relationship with the island. There are about 30 in each group.

There was a problem: "You can't take a 70-year-old woman who never dived and threw it in an open ocean."

Fortunately, there is a solution. This is called simulated diving. "You hold your breath and put your face in a bowl filled with cold water, and your body seems to be diving. Your heart rate will drop."

Haenyeo found the experiment a little stupid. "They said they went into the seabed, and it was diving. What was this, it wasn't diving," Iraldo recalled. "But they still breathed long enough that we could elicit a response."

This reaction is important: Heinho's heart rate is about 50% higher than his non-diving peers. "We have a diver whose heart rate drops 40 times a minute in 15 seconds," said Iraldo.

She concluded that this was a classic physiological adaptation. That's because the heart rate of other female cohorts from Jeju Island (non-genetics with similar genetic composition) did not drop in the same way. The difference between the two groups is due to the lifetime of diving experience.

Push the body to its limit

Next, the researchers collected saliva samples to look for genetic differences between different populations. Everyone in Jeju (whether Haenyeo or non-legendary) basically has the same gene, meaning that people on the island seem to have been carved by generations of divers.

"This shows that everyone on Jeju Island has the potential to be a descendant of divers," Ilardo said.

Two genes stood out in the analysis. The first one seems to be related to cold tolerance. “Maybe this can protect them from ways we don’t quite understand yet to protect their hypothermia,” she advised.

The second gene is related to blood pressure, which may be related to blood vessel structure and function.

“Diver will increase your blood pressure,” said Aguilar-Gómez, who works as a PhD student at UC Berkeley, especially through pregnancy, which can be very dangerous. It may increase your risk of preeclampsia," as well as other potential life-threatening complications.

“Even if you are not dead, women who are likely to be protected are more likely to have more children,” she said.

In addition, one of the lowest stroke mortality rates in Jeju Island is in South Korea. Since stroke may be caused by hypertension, Erado believes that low mortality may be associated with a second protective gene.

“Wouldn’t it be surprising if we could translate these findings into a treatment that protects people from strokes around the world by studying divers in South Korea?” Irado said. “By studying these populations, it can lead to discovery that can have a really important impact on people everywhere.”

Stephen Zhang Studying extreme physiology at Brock University in Canada, without participating in the study. He said he found the work fascinating. “By pushing the body to its limits, we can better understand where these limits are located and how the human body abilities are,” he said.

Irado said she and her team returned to Jeju to share the results with Haenyeo, who is living in a dwindling way of life - and making sure they know the top conclusions.

"These women are extraordinary," she said. "Their biology is amazing, and their work is amazing. So I think it's very important to celebrate the uniqueness and particularity of these women and how to change their bodies and the bodies of others on this island."