The Last Women of the Sea: Diverging Like Marine Mammals

A groundbreaking study highlights the remarkable diving abilities of the Haenyeo women from Jeju, whose underwater endurance rivals that of marine mammals. Their unique physiology and cultural heritage are now at risk as their numbers decline, offering insights into human and marine adaptation.

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Recent research conducted by the University of St Andrews has shed light on an extraordinary group of women known as the Haenyeo, native to Jeju Island off South Korea's coast. These women are renowned for their free-diving skills, descending into the ocean without oxygen to harvest seafood, and their diving prowess rivals that of some marine mammals. They often spend more time underwater than species like sea otters or sea lions, some diving for hours daily.

Published in Current Biology, the study observed seven Haenyeo aged between 62 and 80 years old as they collected sea urchins. Using specialized instruments, similar to those employed in the study of marine mammals, researchers monitored their diving behavior, heart rate, and blood oxygen levels. Remarkably, these women spent about 56% of their diving time submerged during dives that lasted from two to ten hours each day, representing the highest proportion of underwater activity ever recorded in humans.

Interestingly, despite their aquatic lifestyle, the Haenyeo did not exhibit typical mammalian "dive response" patterns—such as slowed heart rates and blood flow reduction. Instead, they showed increased heart rates and only slight oxygen level declines in their brain and muscles. This suggests their unique diving style—characterized by short, shallow, and frequent dives—may involve distinct physiological adaptations.

Lead researcher Dr. Chris McKnight remarked on their impressive capabilities, emphasizing how using aquatic animals as a comparative framework helps illustrate the extraordinary nature of the Haenyeo. These women hold cultural significance and are recognized by UNESCO as an intangible cultural heritage. However, their numbers are dwindling, with over 90% of current divers being over 60 years old.

Co-author Dr. Melissa Ilardo from the University of Utah expressed gratitude to the women for sharing their lives and stories, highlighting the cultural and physiological insights gained from their participation. As potentially the last generation of Haenyeo, this research not only documents a fading tradition but also showcases human resilience and adaptability beneath the waves.