Genetic Adaptations of Haenyeo Divers in Jeju

Recent research has brought into light the unique genetic and physiological traits of the Haenyeo, a group of female divers from Jeju Island, South Korea. Known for their remarkable ability to dive for shellfish, the Haenyeo have been recognised for their cultural significance and were included in UNESCO’s ‘Intangible Cultural Heritage’ list in 2016. This study, published in the journal Cell Reports, investigates how long-term diving practices have influenced their genetic makeup and health outcomes.

Haenyeo Culture and Diving Practices

The Haenyeo are renowned for their exceptional diving skills. They can dive to depths of 10 metres and hold their breath for up to seven hours daily. This lifestyle has encourageed a unique culture that defies traditional gender roles in South Korea. The community’s practices have been passed down through generations, preserving both their cultural identity and diving expertise.

Study Methodology

Researchers examined 91 women divided into three groups – 30 Haenyeo divers, 30 non-diving women from Jeju, and 31 non-diving women from Seoul. The study measured various physiological parameters, including spleen volume, blood pressure, and heart rate responses during simulated dives. This comprehensive approach aimed to identify the effects of diving on the body.

Physiological Findings

The study revealed that Haenyeo divers exhibited a more pronounced bradycardic response during simulated dives compared to control groups. This indicates a robust diving reflex developed through extensive training. However, spleen sizes were similar across Haenyeo and non-diving Jeju women, suggesting environmental factors rather than genetic adaptation influenced this trait.

Blood Pressure and Genetic Variants

Both Haenyeo and Jeju controls displayed higher diastolic blood pressure than Seoul participants, indicating a potential adaptation to enhance blood flow during dives. Whole-genome sequencing of 84 individuals confirmed that Jeju residents are genetically distinct from mainland Koreans, diverging approximately 5,000 to 7,000 years ago.

Implications of Genetic Findings

The researchers identified several gene variants associated with diastolic blood pressure during diving, particularly the variant rs66930627. This variant was more prevalent among Jeju residents and linked to lower diastolic pressure, suggesting an evolutionary adaptation to reduce hypertension risks during pregnancy. This finding supports the hypothesis that natural selection has favoured traits in Haenyeo women to mitigate preeclampsia risks while diving.

Significance of the Study

This research puts stress on the interplay between culture and genetics. The Haenyeo’s unique lifestyle has potentially influenced the genetic evolution of their community. Their ability to dive during pregnancy marks the extraordinary adaptations that have emerged over generations.

Questions for UPSC:

1. Discuss the role of traditional practices in shaping gender roles within societies, using the Haenyeo as a case study.
2. Critically examine the impact of environmental factors on physiological adaptations in human populations, with reference to the Haenyeo divers.
3. Explain the significance of genetic diversity among isolated populations and its implications for public health.
4. With suitable examples, discuss how cultural practices can influence genetic selection in human communities over time.

Answer Hints:

1. Discuss the role of traditional practices in shaping gender roles within societies, using the Haenyeo as a case study.

1. The Haenyeo culture defies traditional gender roles in South Korea, empowering women as primary breadwinners.
2. Women engage in physically demanding diving work, showcasing strength and resilience traditionally associated with men.
3. This unique role has been preserved through generations, challenging societal norms and expectations regarding gender.
4. The Haenyeo community’s recognition by UNESCO marks the cultural significance and the importance of preserving such practices.
5. Their practices promote a sense of identity and solidarity among women, reinforcing their role in both family and community life.

2. Critically examine the impact of environmental factors on physiological adaptations in human populations, with reference to the Haenyeo divers.

1. The Haenyeo exhibit physiological traits such as enhanced bradycardia due to extensive diving training, influenced by environmental demands.
2. Similar spleen sizes between Haenyeo and non-diving Jeju women suggest environmental factors rather than genetic adaptation influence this trait.
3. Higher diastolic blood pressure in Haenyeo may be an adaptation to optimize blood flow during dives, responding to environmental stressors.
4. The study indicates that long-term exposure to cold water may drive physiological changes in heart rate and blood pressure regulation.
5. These adaptations highlight the dynamic interplay between environment and human physiology, impacting health outcomes in specific populations.

3. Explain the significance of genetic diversity among isolated populations and its implications for public health.

1. Genetic diversity in isolated populations, like the Haenyeo, can reveal unique adaptations to environmental challenges, informing health strategies.
2. The distinct genetic variants found in Jeju residents may provide vital information about disease resistance and susceptibility, particularly during pregnancy.
3. About genetic diversity aids in developing targeted public health interventions that consider specific population needs.
4. The study marks the importance of preserving genetic diversity to enhance resilience against health issues like hypertension and preeclampsia.
5. Genetic research in isolated groups can also contribute to broader knowledge about human evolution and adaptation, guiding future health policies.

4. With suitable examples, discuss how cultural practices can influence genetic selection in human communities over time.

1. The Haenyeo’s diving culture may have favored genetic traits that enhance cardiovascular health, such as the rs66930627 variant for lower blood pressure.
2. Traditional practices like diving during pregnancy have exerted selective pressures, promoting traits that mitigate health risks for both mothers and infants.
3. Other examples include the genetic adaptations of populations in high-altitude regions, where cultural practices of living at altitude influence traits like oxygen utilization.
4. Cultural dietary practices can also affect genetic selection, as seen in populations that have adapted to lactose tolerance due to dairy farming traditions.
5. This interplay between culture and genetics puts stress on the significance of understanding human adaptation in the context of evolving lifestyles and environments.