Sea nomad genes are made for life under water
The Sama-Bajau people’s every day life is almost solely under water. And over 1,000 years, evolution has adapted their genes to diving.
The Sama-Bajau people, who live in South East Asia, spend their lives in or on the water. They live on houseboats, and their working days are spent under water. A SamaBajau almost only feeds on fish and shellfish, which he captures by diving to depths of 70 m and keeping his breath for up to five minutes.
Scientists from the University of Copenhagen have revealed that over the past 1,000 years, the people’s life style has made their bodies adapt to life under water. The scientists studied the Sama-Bajau people’s genes to see if they included changes that improve the diving reflex: a survival mechanism that sets to work, when we keep our breath under water. The reflex involves a lower cardiac rhythm, as blood vessels in arms and legs contract, so oxygen-rich blood flows to important organs such as the heart and brain. Moreover, the spleen contracts, releasing its reserves of oxidized blood cells.
The scientists studied 59 individuals, who they compared to a control group from the closely related Saluan people, who are not divers. Scans revealed that a Sama-Bajau spleen was some 50 % larger, and that two gene variants were very common: one that influences the size of the spleen and one which affects blood vessel contraction.
The result indicates that over a very short period of time, evolution produced gene variants that are beneficial in the struggle to survive.