Breathing ...

The secret behind the ability of a group of “sea nomads” in Southeast Asia to hold their breath for extraordinary periods of time while freediving to hunt fish has finally been revealed – and it’s down to evolution ....Genetic testing revealed that certain versions of genes are more commonly found in Bajau people than would be expected, with many apparently linked to biological changes that could help individuals cope with low-oxygen conditions.
Among them is a form of a gene linked to an increased spleen size – an effect the team reveal is likely down to an increase in thyroid hormone levels. Crucially, a contraction of the spleen is one of the features of the so called “diving reflex” – a set of responses in mammals that occur when the head is submerged. A large spleen means even more oxygen-carrying red blood cells can be pumped into the circulatory system when the organ contracts, allowing individuals to stay underwater for longer.