On an archipelago in Southeast Asia live the Bajau, an ancient people world-renowned for a unique cultural tradition. Every work day, the Bajau dive hundreds of feet below water to harvest fish and octopuses from the sea floor. To do so, they must hold their breath on the order of minutes.

Ancient epics describe the Bajau originating from a land-based community dispatched onto the sea, stranded after a fruitless search for an abducted princess. These oral epics placed the Bajau’s origin at an uncertain point in time, and it was not until Magellan’s voyage around the world in 1521 that the Bajau were officially documented in historical records.

Melissa Ilardo, of the Center for GeoGenetics, predicted that the Bajau had been seafaring long enough for diving advantages to emerge as heritable traits in the community. After all, the culture’s survival relies heavily upon harvesting food from the ocean’s depths; if a genetic diving advantage arose by chance, it would probably enhance survival and persist in the community for future generations. Ilardo told Berkeley News that “the closest thing to the Bajau in terms of underwater working time is sea otters; they are also spending about 60% of their time in the water. That is really remarkable, even compared to other professional or traditional divers.”

Armed with a portable ultrasound machine and DNA isolation kit, Ilardo set out to measure traits unique to extreme diver physiology.