What Makes South Korea's 'Super Divers' Special?

Summary

Exploring the Extraordinary Haenyeo of Jeju Island

In the June 20, 2025 episode of NPR's Short Wave, hosts Emily Kwong and science reporter Ari Daniel delve into the fascinating world of South Korea's Haenyeo, the island's remarkable female free divers. This in-depth exploration uncovers the unique physiological and genetic adaptations that enable these women to perform their demanding underwater tasks, as well as the broader health implications of their extraordinary abilities.

The Haenyeo: Masters of the Underwater World

The episode opens with Emily Kwong introducing Ari Daniel, who transports listeners to Jeju Island, located about 50-60 miles off the South Korean coast. Ari Daniel describes a scene where an older woman in a wetsuit expertly dives into the chilly waters without an oxygen tank, relying solely on her lung capacity. Emily Kwong remarks with awe, “Two to three minutes?” (01:17), highlighting the impressive breath-holding capabilities of the Haenyeo.

The Haenyeo are a long-standing tradition on Jeju Island, where these women collect a variety of seafood such as abalone, sea urchins, and seaweeds. Ari likens their underwater activities to "marine grocery shopping" (01:34). These divers operate in waters that can be as cold as 50 degrees Fahrenheit, a condition that adds to the challenge of their daily dives.

Uncovering Physiological and Genetic Adaptations

Melissa Elardo, an evolutionary geneticist from the University of Utah, plays a pivotal role in the episode. She explains that the Haenyeo’s abilities are not solely the result of extensive training but also stem from unique physiological and genetic adaptations. Ari Daniel summarizes Melissa’s findings, stating that the Haenyeo’s diving prowess is a combination of lifelong practice and inherent biological traits (04:36).

The research, published in the journal Cell Reports, compares the Haenyeo to other elderly women on Jeju Island who do not dive and to women from other regions. The study involved around 30 women in each group and utilized a sea stimulated dive technique, where participants hold their breath in a bowl of cold water to trigger the mammalian diving reflex—a natural response that slows the heart rate to conserve oxygen.

Melissa Elardo shares an anecdote about a Haenyeo whose heart rate dropped by over 40 beats per minute in just 15 seconds during the experiment (07:18). This significant reduction was approximately 50% more than that observed in non-diving participants, demonstrating a clear physiological adaptation resulting from their diving lifestyle.

Genetic Insights and Health Implications

Delving deeper, the study revealed that all women from Jeju Island, both divers and non-divers, share a similar genetic background. This indicates that the island's population has been genetically sculpted by generations of divers (08:00). Two key genetic findings emerged:

1. Cold Tolerance Gene: This gene appears to protect the Haenyeo from hypothermia, although its exact mechanisms remain unclear (08:13).

2. Blood Pressure Regulation Gene: Associated with blood vessel structure and function, this gene likely offers protection against conditions like preeclampsia during pregnancy—a significant health advantage for the diver women (08:24).

Steven Chung, an expert in extreme physiology, comments on the potential global health benefits of these findings. He suggests that understanding these genetic adaptations could lead to therapies that protect against strokes, which are often caused by high blood pressure (09:07).

The Future of the Haenyeo Tradition

Despite their remarkable abilities, the Haenyeo tradition is waning as younger generations pursue education and different career paths. The average age of active Haenyeo has risen to around 70 years old, making their numbers increasingly rare (10:13). Melissa Elardo emphasizes the importance of recognizing and celebrating these women’s unique contributions, noting that their biological adaptations have significant implications both locally and globally (10:46).

Conclusion: Celebrating Human Resilience and Adaptation

The episode concludes with a reflection on the exceptional nature of the Haenyeo. Emily Kwong expresses gratitude for the insights provided by Ari Daniel and the research team, underscoring the value of studying such outliers to unlock broader scientific and medical advancements.

Melissa Elardo aptly encapsulates the episode’s message: “These women are extraordinary. Their biology is amazing and what they do is amazing” (10:46). This celebration of human resilience and adaptation highlights how the Haenyeo of Jeju Island exemplify the incredible potential of the human body when honed by tradition and necessity.

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By shedding light on the Haenyeo, NPR’s Short Wave not only honors these women’s remarkable skills but also opens the door to understanding how extreme lifestyles can drive both physiological and genetic evolution, offering valuable lessons for the world at large.

Transcript

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[Emily Kwong]

You're listening to Shortwave from NPR. Hey, everybody, it's Emily Kwong, and I'm with science reporter Ari Daniel. You're taking us on an adventure today, right, Ari?

[Ari Daniel]

I am indeed, Emily. I'm going to take you to Jeju Island.

[Sponsor Message]

Ooh.

[Emily Kwong]

Where's Jeju island?

[Ari Daniel]

It's like 50, 60 miles off the coast of South Korea. And in this video that you're hearing, there's a motorboat that's chugging along the coast. Before the vessel even comes to a stop, an older woman in a wetsuit jumps into the water and dives down.

[Emily Kwong]

Oh, so this is a diver?

[Ari Daniel]

Yeah.

[Emily Kwong]

Cool. I'm assuming she's also got fins and a mask?

[Ari Daniel]

Yes. Yep. Yes.

[Emily Kwong]

And like an oxygen tank and stuff?

[Ari Daniel]

No, just pure lung capacity. This woman is part of a long line of female free divers on Jeju island called the Haenyeo. And these women can hold their breath a really long time, Emily. Up to two or three minutes.

[Emily Kwong]

Two to three minutes?

[Ari Daniel]

Minutes.

[Emily Kwong]

What are the Haenyeo doing down there?

[Ari Daniel]

They're collecting all kinds of seafood to eat and sell.

[Melissa Elardo]

Things like abalone, sea urchins, you know, harvest seaweeds.

[Emily Kwong]

Sometimes it's like grocery shopping while holding your breath.

[Ari Daniel]

Marine grocery shopping. Exactly.

[Emily Kwong]

Yeah.

[Ari Daniel]

This is Melissa Elardo. She's an evolutionary geneticist at the University of Utah, and she sent me this video that she took of a few Haenyeo divers who routinely dive in waters that can be in the 50 degree range.

[Emily Kwong]

Oh, so they're diving in really cold water?

[Ari Daniel]

Yeah. I mean, I could never do it. I mean, I can barely handle 70 degree water. But these women, they start diving as girls and continue well into old age. And what's astonishing is that it's not just years of training that make this feat possible. It's also a set of special adaptations, ones that Melissa and her team recently uncovered.

[Emily Kwong]

So today on the show, the super divers of Jeju Island.

[Ari Daniel]

Plus the mix of physiological and genetic adaptations that make these women's dives possible.

[Emily Kwong]

I'm Emily Kwong.

[Ari Daniel]

And I'm Ari Daniel, and you're listening.

[Emily Kwong]

To Short Wave from npr. So, Ari, today we're talking about the Haenyeo, these female free divers in South Korea. How do the Haenyeo compare to other freedivers around?

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[Emily Kwong]

What makes their abilities so special?

[Ari Daniel]

I mean, free diving anywhere is tough, Emily, but the conditions that the Haenyeo are operating under are pretty extreme.

[Melissa Elardo]

One of the first times I was there, it was. It was snowing. 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.

[Ari Daniel]

That's commitment indeed. And these women dive across all of life's milestones, which I talked to Melissa and her collaborator, Diana Aguilar Gomez about. Diana is a population geneticist currently at ucla.

[Steven Chung]

They dive throughout their whole pregnancy. They say they just dive until basically before they give birth, and then they.

[Melissa Elardo]

Were back in the water three days later.

[Steven Chung]

Yeah, it's amazing.

[Ari Daniel]

Diana and Melissa wanted to know whether there were adaptations the Haenyo might have that allow them to do this. And they recently pinpointed some in a study that published in the journal Cell Reports.

[Emily Kwong]

Fascinating. Okay, how did that study come about?

[Ari Daniel]

Well, Melissa Elardo, she runs something called the super Human Lab, where she studies extreme physiologies across different populations and including among the bajau free divers in Indonesia.

[Melissa Elardo]

They're just really good at holding their breath and being underwater. And we found that the bajau had larger spleens, and we were able to link this to a genetic adaptation. And so the spleen plays a role in diving because it stores red blood cells that are oxygenated. And when you dive, your spleen contracts and it pushes those red blood cells into circulation. So essentially, we think the Bajau have big spleens because it enables them to stay underwater longer.

[Ari Daniel]

Melissa told me the Bajau were the first group of people that were Found to have evolutionary adaptations to make this kind of diving safer. And she wanted to know how the haenyeo might be adapted to their extreme.

[Melissa Elardo]

Lifestyle, how evolution might have shaped the haenyeo to be better divers, to dive more safely, to dive for longer.

[Emily Kwong]

Yeah, it's so impressive that they can do this. So how did Melissa and her team go about conducting this study?

[Ari Daniel]

Well, they decided to compare the haenyeo to other elderly women on the island who aren't divers, but have a similar. Similar genetic background and distill others off island who aren't related. About 30 women in each group.

[Emily Kwong]

Okay, so they had some groups of non divers to compare to the divers. So how did they compare them? Because you, I assume they didn't just throw all these elderly women into the open ocean and hope for the best.

[Ari Daniel]

They certainly did not try that approach. Fortunately, there's a workaround, a safer workaround. It's called a sea stimulated dive.

[Melissa Elardo]

You hold your breath and put your face in a bowl full of cold water, and your body responds as if you're diving. Your heart rate will drop measurably.

[Emily Kwong]

I've done this when I'm very anxious. But why does your heart rate drop when you put your head in a bowl of ice water?

[Ari Daniel]

It's just an automatic thing, Emily. Your body acts like it's underwater and triggers something that's called the mammalian diving reflex, which slows down your heart rate, allowing it to do less work to limit oxygen consumption. The henyo, though, they found this experiment kind of silly.

[Melissa Elardo]

They said, like getting in the ocean, being underwater. That's diving. Whatever this is, this isn't diving. But they still held their breath long enough that we were able to elicit a response.

[Emily Kwong]

I'm just picturing all these aunties and grandmas, like for science, I guess, if I have to. But. So what was the response between the haenyeo and the non divers?

[Ari Daniel]

In doing this, there was a significant one. The haenyo heart rate fell by about 50% more than their non diving PE.

[Emily Kwong]

Wow.

[Melissa Elardo]

We had one diver whose heart rate dropped over 40 beats per minute in 15 seconds.

[Ari Daniel]

Melissa says the henyo response is due to a lifetime of training and diving experience. So it's classic physiological adaptation.

[Emily Kwong]

What about genetic adaptation? Did they do an analysis of those women on the level of their DNA as well?

[Ari Daniel]

They did. The researchers took saliva samples to look for genetic differences between the three groups. And they found that everyone from Jeju, both the divers and non divers, had basically the same genes. Meaning that the people of the island appear to have been genetically sculpted by generations of divers.

[Melissa Elardo]

What this suggests is that everybody in Jeju has an equally likely chance of being a descendant of a diver.

[Emily Kwong]

What a thing to inherit. And was there anything special about this particular gene pool that stood out?

[Ari Daniel]

Yeah, two things, actually. The first was a gene that seems to be related to cold tolerance, maybe.

[Melissa Elardo]

That protects them from hypothermia in ways that we don't fully understand yet.

[Emily Kwong]

That makes sense.

[Ari Daniel]

Right? And the second gene is associated with blood pressure, which Diana Aguilar Gomez, who did this work as a PhD student at UC Berkeley, thinks is likely connected to blood vessel structure and function.

[Steven Chung]

Diving increases your blood pressure, and particularly through pregnancy. That can be very dangerous. It can increase your risk for preeclampsia.

[Ari Daniel]

So if these women have a gene that lowers their blood pressure, it's like built in protection from preeclampsia and other life threatening complications.

[Steven Chung]

And so probably women that would protect it against this would be more likely to have more children.

[Emily Kwong]

Oh, and they would pass those genes along.

[Ari Daniel]

Bingo. And I should tell you, Emily, that Jeju island has an especially low rate of stroke mortality. And Melissa thinks that could be related to this second protective gene, since stroke can result from high blood pressure.

[Melissa Elardo]

Wouldn't it be amazing if by studying divers in Korea, we can translate these findings to develop a therapeutic that protects people from stroke around the world? So by studying these populations, it can lead to discoveries that could have really important implications for people everywhere.

[Emily Kwong]

Absolutely. This is so the value of studying outliers. So what health lessons can be learned from these free divers?

[Ari Daniel]

So I spoke with Steven Chung, who studies extreme physiology at Brock University in Canada. He wasn't involved in the research, but he addressed this exact question. By pushing the body to its limits, we get a better sense of where those limits are, but also just what the human body is capable of.

[Steven Chung]

I'm not even near the age of these women and I don't think I can go and dive all day. I mean, I feel like that's like a superpower.

[Ari Daniel]

A superpower that Diana says may not be around for much longer.

[Steven Chung]

The newer generations of women, they're like going to university and doing other stuff. So like the average age of the genio nowadays is around 70 years old.

[Emily Kwong]

Oh, wow. So this is just becoming an increasingly rare practice, even if the genetics live on in the descendants of these divers.

[Ari Daniel]

That's true. And it's one of the reasons that it was important to Melissa that her and her team returned to Jeju island to share their results with the Haenyeo.

[Melissa Elardo]

These women are extraordinary. Their biology is amazing and what they do is amazing. And so I think it's really important to celebrate just how unique these women are and how it's changed their bodies and the bodies of other people on this island.

[Emily Kwong]

Ari Daniel, thank you so much for coming on Shortwave. I'm really glad we know more about the Haenyo.

[Ari Daniel]

Thanks for having me, Emily. I love being here.

[Emily Kwong]

If you liked this episode of Shortwave and you want to support the show, follow us on the NPR app or wherever you get your podcasts and you'll never miss an episode. This episode was produced by Hannah Chin, it was edited by our showrunner Rebecca Ramirez, and fact checked by Tyler Jones. Jimmy Keeley was the audio engineer, Beth Donovan is our Senior director and Colin Campbell is our senior Vice President of Podcasting Strategy. I'm Emily Kwong. Thank you for listening to Short Wave. From.

[Melissa Elardo]

Foreign.

[Diana Aguilar Gomez]

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