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.

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.