This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study combines paleoanthropology and diving physiology to address a fundamental question in human evolution: Why did humans evolve their exceptional aerobic endurance? Did our ancestors begin endurance running to exhaust terrestrial prey, or did breath-hold diving for aquatic resources also play a key role?
Drawing on comparative physiology, anatomy, paleoecology and paleoanthropology, researchers Josephine Joordens and Erika Schagatay propose a new "dive first, run later" hypothesis. In their study, they challenge and modify the popular endurance running hypothesis, arguing that the origin of human stamina cannot be understood from land-based foraging alone. The study will be published in PaleoAnthropology.
"When studying the origin of human endurance and the evolutionary history of the Homo sapiens lineage, it is imperative to take not only endurance running, but also endurance diving for food, into account," they argue. Humans are unusual among primates. Not only are we capable endurance runners, but we are also strong long-distance swimmers and skilled breath-hold divers.
Modern populations of freedivers, such as the Ama and the Sama-Bajau, demonstrate that humans can repeatedly dive for hours to hunt fish and gather shellfish and other aquatic resources. This form of repeated breath-hold diving is described in the study as "endurance diving": making repeated dives with short breathing pauses at a regular pace to minimize recovery time at the surface and maximize time spent underwater, where resources are available. Japanese Ama divers, for instance, gather shellfish such as abalone and turbo shells by repeatedly diving to shallow depths.
A 2-hour time-depth recording of an Ama diver's working shift shows 50 dives to depths of around 8–10 meters (26–33 feet), with 45% of the time spent underwater. "This diving method enables individuals to work underwater for hours each day while holding their breath," says Schagatay, a professor of animal physiology and a specialist in human performance in hypoxic environments, such as breath-hold diving and high-altitude environments. The endurance running hypothesis, which was first put forward by Bramble and Lieberman in 2004, remains one of the main textbook explanations for why humans became so different from other apes.
According to this hypothesis, characteristics such as long legs, effective cooling mechanisms and increased aerobic capacity evolved as a result of early humans hunting terrestrial prey by pursuing animals over long distances. Joordens and Schagatay do not dismiss the endurance running hypothesis outright. Instead, they argue that this explanation may be incomplete.
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