Diving Like Sea Otters May Have Helped Our Ancestors Build the Stamina to Run

Researchers suggest that diving for food may have contributed to the development of endurance in our ancestors, ultimately aiding their capacity for long-distance running. Erika Schagatay, a physiologist, observed Sama-Bajau communities in Southeast Asia diving with circular leg strokes while gathering food, surfacing to breathe repeatedly.

This underwater activity was a recurring part of their lives, sometimes extending for hours. Schagatay and paleoanthropologist Josephine Joordens propose the "dive first, run later" hypothesis, suggesting that the demands of underwater diving could have helped our ancestors build the heart and lung capacity used later for running.

This hypothesis expands on the idea that human stamina evolved by chasing prey until they became too exhausted to escape, potentially developing partially in water first. The researchers found that human diving patterns closely resemble those of shallow-diving, semi-aquatic mammals such as sea otters. They argue that repeated diving could have favored ancestors whose bodies efficiently replenished and conserved oxygen, possibly explaining why some early humans had heavier bones to counter buoyancy while diving.

The researchers note that the endurance seen in modern Sama-Bajau communities, who dive into their 60s and 70s, provides a living example of the endurance they are studying in our ancestors.