News

Haenyeo sing traditional songs before heading out to sea to harvest abalone, sea urchins, seaweed, and other seafood from the waters around Jeju Island, South Korea

Scientists studying the DNA of the famous female freedivers of Jeju Island—the haenyeo—have discovered there are unique genetic differences that the women have evolved to cope with the physiological stress of freediving. Published in the scientific journal Cell Reports on May 2, 2025, the research was led by Melissa Ann Ilardo, a geneticist and assistant professor in biomedical informatics at the University of Utah.

Ilardo and her colleagues recruited 30 haenyeo divers, 30 non-diving women from Jeju Island, and 31 women from the South Korean mainland for the study. The participants’ average age was 65. As well as sequencing their genomes from blood samples, the researchers compared their heart rates, blood pressure and spleen sizes. In order to simulate dives, participants held their breath while submerging their faces in cold water, stimulating the mammalian dive reflex. As a result, the heart rate slows, blood pressure increases and the spleen contracts.

The analysis showed that the participants from Jeju—divers as well as non-divers—were more than four times more likely than the participants from the mainland to have a genetic variant associated with lower blood pressure. “Your blood pressure increases as you dive,” explains Ilardo. “Their [Jeju residents’] blood pressure increases less.” The scientists suggest that the genetic trait may have evolved to keep unborn babies safe—since the haenyeo dive throughout pregnancy, when high blood pressure can be dangerous.

Previous research has linked cold and pain tolerance to another genetic variation, and this study revealed that the participants from Jeju were more likely to have this genetic variant. However, the researchers weren’t able to say with certainty whether the variant may be important for the haenyeo’s ability to dive throughout the year, since the participants’ ability to withstand low temperatures was not measured in the study.

Genetics wasn’t the only factor to explain the haenyeo’s impressive diving capabilities. During the tests, the researchers also found a dramatic difference between the heart rates of the divers versus the non-divers. A reduced heart rate would help the haenyeo conserve oxygen during their dives. “Actually, their heart rate dropped about 50% more over the course of the dive than the control (participants),” says Ilardo. “We know that it’s because of training, because it’s something that we only saw in the haenyeo.”

While much more work needs to be done, the research could potentially lead to the development of new drugs for lowering blood pressure.

Read more here.