A new paper published in Cell finds that the spleens of the Bajau people, the Sea Nomads of Island Southeast Asia, are significantly larger than their land-based neighbours, which has been the result of many generations of natural selection. Larger spleen size helps in diving by providing extra oxygenated blood into the body.
Physiological and Genetic Adaptations to Diving in Sea Nomads
Understanding the physiology and genetics of human hypoxia tolerance has important medical implications, but this phenomenon has thus far only been investigated in high-altitude human populations. Another system, yet to be explored, is humans who engage in breath-hold diving. The indigenous Bajau people (“Sea Nomads”) of Southeast Asia live a subsistence lifestyle based on breath-hold diving and are renowned for their extraordinary breath-holding abilities. However, it is unknown whether this has a genetic basis. Using a comparative genomic study, we show that natural selection on genetic variants in the PDE10A gene have increased spleen size in the Bajau, providing them with a larger reservoir of oxygenated red blood cells. We also find evidence of strong selection specific to the Bajau on BDKRB2, a gene affecting the human diving reflex. Thus, the Bajau, and possibly other diving populations, provide a new opportunity to study human adaptation to hypoxia tolerance.
- Mystery of sea nomads’ amazing ability to freedive is solved (The Guardian | 19 April 2018)
- ‘Sea Nomads’ Are First Known Humans Genetically Adapted to Diving (National Geographic | 19 April 2018)
- Natural selection gave a freediving people in Southeast Asia bigger spleens (Science Daily | 19 April 2018)