Overview
This lecture discusses human adaptations to low-oxygen environments, focusing on the Bajau people's ability to dive underwater for extended periods due to larger spleens and related genetic factors.
Human Adaptation to Low Oxygen
- Humans have developed ways to carry more oxygen in the blood to survive in high-altitude and underwater environments.
- High-altitude populations adapt by enhancing blood’s oxygen-carrying properties.
The Bajau People and Diving
- The Bajau, or “Sea Nomads,” traditionally dive for long periods without breathing equipment.
- Bajau divers may spend up to 60% of their workday underwater.
Physiology of the Dive Reflex
- The dive reflex is triggered when mammals submerge their faces in water.
- Heart rate slows, peripheral blood vessels constrict, and blood is redirected to vital organs during a dive.
- The spleen contracts, releasing oxygen-rich red blood cells into circulation.
Spleen Size and Oxygen Storage
- Bajau people have spleens about 50% larger than those of neighboring land-based populations.
- Larger spleens serve as reservoirs for extra oxygenated blood during dives.
Genetic Factors in Spleen Size
- Researchers identified 25 genetic differences between the Bajau and nearby populations.
- The PDE10A gene, linked to thyroid activity, appears to influence spleen size.
- Evidence suggests spleen enlargement in the Bajau is at least partly genetic.
Broader Implications
- Human bodies have adapted to low-oxygen conditions through different strategies, including at high altitudes and in underwater environments.
Key Terms & Definitions
- Bajau — A group of sea-dwelling people known for their deep-diving abilities.
- Dive Reflex — A set of physiological responses that conserve oxygen when submerged in water.
- Spleen — An organ that can store and release red blood cells, aiding in oxygen delivery during dives.
- PDE10A Gene — A gene that may influence spleen size via effects on thyroid activity.
Action Items / Next Steps
- Review genetic adaptation mechanisms in other human populations.
- Read about oxygen transport and storage in mammalian physiology.