Understanding the physiology and genetics of how humans handle low levels of oxygen has, to date, yielded lots of useful medical information. The populations that researchers have studied for this sort of work have been exclusively those dwelling at exceedingly high altitudes. Yet a team noted that there are some humans who have routinely been denied oxygen by having to hold their breath to find food. Curious about what sorts of effects a breath holding lifestyle has on our biology, the researchers took at fascinating look at the indigenous Bajau people.
Known as the Sea Nomads of Southeast Asia, the Bajau have extraordinary breath holding abilities and use these abilities to collect food from the ocean. What has been mysterious is whether they are born with these abilities or whether they gain them through training.
Using a comparative genomic study, the team found that the Bajau carry genes that lead them to have much larger spleens than the rest of us. This is important because the spleen is responsible for providing us with the red blood cells that carry oxygen around and having more of these cells enables us to last for a longer time without breathing. Thus, the larger spleens allow the Bajau to have a huge reservoir of oxygenated red blood cells that dramatically increase their diving abilities. Thus, it would seem that the Bajau are literally born to dive. You can read more in The Economist article that I wrote on this here.