• Jeju Island's Haenyeo divers exhibit genetic adaptations related to cold tolerance and blood pressure regulation, possibly evolved to protect pregnant divers.
• The study identified a genetic variant associated with lower blood pressure during simulated dives in Jeju Islanders (both divers and non-divers), potentially offering insights for blood pressure disorder treatments.
• Haenyeo divers also show physiological adaptations like slower heart rates during dives, attributed to lifelong training, and researchers suggest potential medical applications of these genetic and physiological adaptations.

A new study published in Cell Reports has uncovered genetic and physiological adaptations in the Haenyeo, the 'sea women' of Jeju Island, South Korea, who have practiced free diving for generations. The study compared the genomes and physiological responses of Haenyeo divers, non-diving Jeju residents, and mainland South Koreans. Findings indicate that Jeju Islanders possess unique genetic variations that contribute to cold tolerance and help regulate blood pressure during diving, potentially protecting them from diving-induced hypertension and offering insights into cardiovascular health. The Haenyeo's traditional practices, coupled with their unique genetic makeup, make them a valuable subject for understanding human adaptation to extreme environments.

• What: Study reveals genetic adaptations in Jeju Island's Haenyeo divers, including variants related to cold tolerance and blood pressure regulation during diving. The divers also show physiological adaptations due to training, such as slower heart rates.
• Who: Melissa Ilardo (University of Utah) led the study, collaborating with researchers from South Korea, Denmark, and the United States. Participants included Haenyeo divers, non-diving Jeju residents, and mainland South Korean women. Key figures also include Tatum Simonson (UC San Diego Health) and Ben Trumble (Arizona State University).
• When: The study was published in Cell Reports on May 2, 2025. The Haenyeo have been diving for generations, with current divers averaging around 70 years old.
• Where: The study focuses on Jeju Island, South Korea, where the Haenyeo divers live and work. Genetic comparisons were made with mainland South Korean women.

The study provides valuable insights into how humans adapt to extreme environments through both genetic evolution and physiological training. The genetic adaptations observed in the Haenyeo, particularly those related to blood pressure regulation, could have significant implications for treating cardiovascular diseases. The cultural aspect of the Haenyeo, with their matrilineal diving tradition, highlights the intersection of genetics, environment, and culture. The decline in young women continuing the diving tradition raises concerns about the potential loss of this unique genetic and cultural heritage. Further research is needed to fully understand the medical implications of these adaptations and to explore similar adaptations in other diving populations.

It's incredible. It's not just that they're doing this in older age, but how athletically they're doing it is just mind blowing.

When you’re diving, your blood vessels are responding in complicated ways to try to keep your vital organs safe as your oxygen is running low. It becomes a trade-off between short term and long term benefits — what keeps you safe while you’re diving might lead to complications further down the line. Evolution seems to have found a way to balance this out — a genetic variant that may protect divers while they’re holding their breath and beyond.

We think … evolution acted to protect these pregnant women while they were diving. Their diastolic blood pressure did not increase as much as people with a different genetic background. And that was regardless of training.

There’s something biologically different about them that makes them extremely special, no matter how you characterize it, and what they do is unique and worth celebrating.

The study of Jeju Island's Haenyeo divers reveals a compelling interaction of genetic adaptation, physiological training, and cultural heritage in response to extreme marine environments. Genetic variations associated with cold tolerance and reduced diastolic blood pressure, potentially mitigating hypertension risks during pregnancy, highlight evolutionary adaptations to the demands of breath-hold diving. Lifelong diving training further enhances their physiological capabilities, demonstrated by significant bradycardia during dives. The Haenyeo's traditional ecological knowledge and sustainable harvesting practices also contribute to the preservation of Jeju's marine biodiversity. However, the aging population of Haenyeo and the decline in younger generations embracing this demanding lifestyle pose a threat to the continuation of this unique cultural tradition and the valuable genetic insights it offers. Focused preservation efforts, coupled with further research into their genetic adaptations, are crucial not only for safeguarding this Intangible Cultural Heritage of Humanity but also for unlocking potential treatments for cardiovascular diseases and for understanding human adaptation to extreme conditions. Further research could explore the potential for translating the Haenyeo's adaptations into medical treatments, while preservation efforts must address the socio-economic factors influencing younger generations' decisions to continue this vital tradition.