The Haenyeo, or "women of the sea," are a group of all-women extreme divers who work off the coast of Korea. They have spent their entire lives free-diving as much as 60 feet under the surface in the waters off Jeju Island, 50 miles south of mainland South Korea. The divers collect foodstuffs like abalone and seaweed from the seafloor, and do so while spending hours in the water every day, year round. There aren't many divers left, because young people haven't been interested in picking the practice up, so they are getting older and most are in their 60s and 70s.
Now, scientists have performed a genetic analysis of the divers to learn more about some of the genetic changes that may have helped them adapt to free-diving and staying in the water for hours. Free-diving takes a toll, and knowing more about how they overcome the difficulties could help scientists find better treatments for some heart disorders. The work has been published in Cell Reports.
In this study, the researchers collected data about blood pressure, heart rate, and other physiological measures, as well as DNA samples. After sequencing the participants' DNA, the researchers found genetic variants that could be helping these women perform their extraordinary feats of endurance and stamina.
Divers obviously cannot breathe while free-diving, and this tends to cause blood pressure to rise. Sleep apnea, where breathing is interrupted during sleep, has been linked to pregnancy-related blood pressure disorders. The divers have continued to dive during pregnancies, and the researchers suggested that a genetic variant in the Haenyeo could be shielding fetuses from harm during dives.
If the genetic variant in the Haenyeo helps lower blood pressure, it may be crucial. They dive throughout pregnancy, so it's vital to avoid blood pressure conditions like preeclampsia, which can be fatal.
"They're absolutely extraordinary women," said senior study author Melissa Ilardo, Ph.D., an assistant professor of biomedical informatics at University of Utah Health. "Every day, they head out and get in the water, and that's where they work all day. I saw women over 80 diving off a boat before it even stopped moving."
Compared to Koreans who live on the mainland, the Haenyeo divers are over four times as likely to carry a genetic variant that is linked to reduced blood pressure during dives.
"This is not something that every human or every woman is able to do," noted first study author Diana Aguilar-Gómez, Ph.D., a postdoctoral researcher in evolutionary biology at University of California, Los Angeles. "It's kind of like they have a superpower."
Another genetic variant found in the divers is related to the tolerance of pain that is caused by cold temperatures. The Haenyeo continue to dive during winter though it gets cold.
Although genetic variants could be helping these women, their strengths come from performing this work for a lifetime; they are experts.
Sources: University of Utah, Cell Reports