Endurance running or endurance diving—which came first?

A new study published in PaleoAnthropology challenges the widely accepted idea that humans evolved endurance running as a primary adaptation for hunting. Researchers Josephine Joordens and Erika Schagatay propose a revised hypothesis that endurance diving may have played a more significant role in shaping human aerobic capabilities.

The study argues that humans are unique among primates in their ability to engage in both endurance running and prolonged breath-hold diving. Modern freedivers, like the Ama and Sama-Bajau, can dive repeatedly for hours at a time while holding their breath. This form of endurance diving, characterized by short breathing pauses and efficient oxygen management, could have driven the evolution of the cardiorespiratory system required for long-distance running.

The researchers suggest that endurance diving may have initially fueled the development of the cardiorespiratory stamina necessary for running. Both divers and high-altitude dwellers share physiological adaptations that help conserve oxygen during hypoxic conditions. These include efficient respiratory and cardiovascular systems, as well as the ability to pace effort and manage lactate buildup.

Interestingly, the study also connects breath-hold diving and high-altitude tolerance, noting that the latter requires a similar capability to conserve oxygen in low-oxygen environments. The researchers propose that modern humans' exceptional fitness in both diving and running may stem from a combination of populations, one specialized in endurance diving and the other in endurance running.

The study also touches on the evolutionary significance of heavy bone mass in early Homo fossils, suggesting that this may have been advantageous for efficient shallow diving rather than intense terrestrial activity. This finding implies that populations with heavy bones may have relied more on underwater foraging, while lighter-built groups focused on running and land-based hunting.

In summary, the new hypothesis posits that the development of human endurance running and diving abilities was likely driven by a combination of land-based and aquatic foraging strategies, shaping the diverse locomotion and foraging techniques observed in contemporary hunter-gatherers.