‘Real-Life Mermaid’ South Korean Divers Have a Remarkable Underwater ‘Superpower’ Written Into Their DNA

Jeju Island in Korea is filled with stunning beauty, but none stand out more than Haenyeo. They are essentially a group of women who plunge deep into the ocean without any equipment, according to Smithsonian Magazine. For a long time, experts have been trying to figure out the secret behind these unique capabilities. Findings published in the journal Cell Reports have finally answered these queries. 

Haenyeo are also popularly known as 'women of the sea.' From a young age, women are trained to go deep into the waters of the island to collect sea snails like abalone, sea urchins, and other food items. These women regularly dive up to 60 feet beneath the ocean's surface, even when they are pregnant. The group remains a staple of the island, but their numbers have significantly dwindled, especially in terms of new joiners. At present, the average age of a Haenyeo woman is around 70 years old. Many in the group believe themselves to be the last of their kind. 

According to the study, Hanyeo's comfort with oceans is a combination of training and genetics. For the study, the experts had 30 Haenyeo divers, 30 older non-diving women on Jeju Island, and 31 older South Korean women from other places as subjects. The team asked all the subjects to perform simulated dives and also took their saliva samples. 

The analysis revealed that three unique adaptations aid Haenyeo women in their diving, according to the DW. One genetic adaptation was found in both the Haenyeo divers and Jeju women. Researchers noted that the genetic trait allows these women to have a protective blood pressure response while diving in water. This implies that their blood pressure did not increase as much as the other women, while diving. This response especially helps pregnant women who are Haenyo divers, as they become less vulnerable to preeclampsia, a pregnancy complication during diving. 

One adaptation was not based on genetics and instead came into being through training. Researchers found that whenever Haenyeo women dived, their heart rate slowed down much more than the other subjects. Experts think these women gained this capability after years of training. 

The adaptation, which involves this slowing down of heart rate, is called bradycardia. In the case of Haenyeo women, it was found to be 60 beats per minute. Melissa Ann Ilardo, a specialist in human biological adaptations at the University of Utah, US, claims that this slowing down of heart rate is a mammalian reflex given by every human after diving. However, in the case of these Haenyeo women, there was a greater heart rate response compared to other subjects. 

The final genetic mutation that allowed Hanyeo women to have a better time in the ocean depths than other subjects was related to cold tolerance, according to the Washington Post. The exercise proved that Haenyeo women had better endurance against cold water. This is essentially because of a variant in the gene called sarcoglycan zeta, as per experts. 

Researchers believe these findings could be useful in developing better treatments for several chronic conditions like cardiovascular diseases. There is a possibility that the genetic adaptations could be the reason behind Jeju Island having the lowest age-standardized stroke death rates in South Korea, around 24 deaths per 100,000 people. Experts are hopeful that further investigation on these adaptations, could give them insights on how to prevent as well as deal with these conditions in patients.