The success of the Netflix drama 'When Life Gives You Tangerines' was supported by Jeju haenyeo. The main character Aesoon (played by IU) had her mother and aunt as strong supporters, both of whom were haenyeo. As the drama gained global popularity, the number of foreigners visiting Jeju for haenyeo experiences has also increased.
Some scientists have also fallen for the Jeju haenyeo. An international research team led by Professor Melissa Ilardo of the University of Utah revealed on the 3rd that they uncovered the secret behind the extraordinary diving abilities of Jeju haenyeo at the genetic level.
This study was conducted by researchers from the University of California, Los Angeles (UCLA), University of California, Berkeley (UC Berkeley), Cornell University, University of Copenhagen in Denmark, and Seoul National University. The results were published that day in the international academic journal 'Cell Reports.'
Jeju haenyeo undergo diving training from around the age of ten and continue to work throughout their lives. They even dive while pregnant. Researchers believe that the haenyeo's exceptional diving ability is a result of long-term training and genetic adaptation. To uncover this, the researchers compared physiological traits and genomes among 30 Jeju haenyeo, 30 non-haenyeo Jeju women, and 31 women living in Seoul.
The average age of the research participants was set at 65 to match that of the Jeju haenyeo. To confirm genetic influences, the haenyeo were selected from families with at least three generations of haenyeo.
The researchers initially asked participants to perform a 'simulated dive.' This involved splashing cold water on their faces and holding their breath. Professor Ilardo explained, "Holding one's breath while immersing the face in cold water elicits a physical response similar to actually being in the ocean" and added that "this is a safe method for people without diving experience to test."
As a result of the simulated dive experiment, the participants' heart rates decreased, particularly among the haenyeo. The haenyeo showed an average decrease of 18.8 bpm (beats per minute), while non-haenyeo Jeju women exhibited a 12.6 bpm decrease. The reduction in heart rate during diving is advantageous for conserving energy and preserving oxygen.
The researchers attributed this difference to the effects of long-term training. Genetic analysis revealed that both Jeju haenyeo and non-haenyeo women belong to the same population group. Therefore, the difference in heart rate changes can be viewed as a result of training. Professor Ilardo stated, "Haenyeo have been trained to reduce their heart rates significantly during extended diving" and noted, "Some Jeju haenyeo had a heart rate decrease of more than 40 bpm in just 15 seconds."
There were also distinct genetic differences between Jeju residents and those from the mainland. Two major genetic differences were identified. One is a gene variant associated with cold tolerance. This gene variant related to the ability to withstand cold water was found in Jeju residents but not in those living in Seoul.
The other difference is a gene variant related to the reduction of diastolic blood pressure when the heart relaxes. Participants from Jeju exhibited a gene variant that lowers diastolic blood pressure by about 10 mmHg. Among Jeju residents, 33% showed this genetic variant, compared to only 7% of Seoul residents.
The researchers speculated that this genetic variant emerged to prevent preeclampsia since haenyeo continue diving even during pregnancy. Preeclampsia is a severe pregnancy complication occurring after 20 weeks of gestation, characterized by high blood pressure and threatening the lives of mothers and fetuses.
Professor Ilardo noted, "Diving during pregnancy could elevate the risk of hypertensive complications" and added, "It seems that the genetic variant of Jeju haenyeo was naturally selected to reduce such risks."
The timing of genetic divergence between Jeju residents and mainland Koreans is estimated to have occurred around 5,000 to 7,000 years ago. During this period, the unique breath-holding diving of Jeju haenyeo influenced the physiological and genetic characteristics of Jeju residents.
Professor Ilardo expressed a desire to understand more deeply how genetic changes influence the health of Jeju residents, stating, "This change could also inspire the development of treatments for conditions such as gestational hypertension or strokes."
References
Cell Reports (2025), DOI: https://doi.org/10.1016/j.celrep.2025.115577