Humans are biologically built to run – scientists reveal why

The 2024 Summer Olympics are underway, and the marathon is one of the standout events, testing fitness and athleticism to the limit. Humans excel at endurance running, ranking among the top mammals in this regard. While not the fastest sprinters, humans can run long distances steadily, even in hot weather. Our muscles are primarily composed of slow-twitch, fatigue-resistant fibers, and our ability to sweat effectively helps us dissipate heat.

Humans seem naturally equipped for endurance running, but why is this the case?

In 1984, biologist David Carrier introduced the endurance pursuit hypothesis to explain our remarkable long-distance running abilities. He suggested that these traits evolved to help us hunt large game animals through persistence hunting.

Two decades later, scientists Dennis Bramble and Daniel Lieberman expanded on Carrier’s theory, identifying specific physiological traits conducive to endurance running. They proposed that these traits emerged nearly 2 million years ago in the Homo genus and may have been crucial in shaping the human body.

However, not everyone agrees with this hypothesis.

“There are two reservations that have always clung to this hypothesis,” said Bruce Winterhalder, professor emeritus at UC Davis. “One is that running is more costly than walking, so based on a simple cost-benefit analysis, it doesn’t look like an efficient way of hunting.”

“And then secondly, we have some examples of contemporary hunter-gatherers practicing endurance pursuits but probably less than a dozen cases,” he added. “For the skeptics, endurance pursuits can’t have been that important to hunting evolution in the Paleolithic if it’s not that important to hunter-gatherers now.”

In a recent study published in Nature Human Behaviour, Winterhalder and paleoanthropologist Eugène Morin of Trent University used mathematical modeling and ethnohistoric investigation to support Carrier’s hypothesis.

Winterhalder highlighted the importance of digitized accounts from explorers, missionaries, and officials, alongside advanced analytical software, in uncovering historical examples of endurance pursuits.

“We have software that allows us to search for information that dwarfs what we could do if we were trying to read through all the possible sources ourselves,” Winterhalder explained.

Using this technology, Winterhalder and Morin found 391 descriptions of hunts, from 1527 to the early 20th century, involving endurance pursuit tactics. These accounts came from 272 locations worldwide, suggesting that such hunting methods were widely practiced and occurred in various environments.

The historical data revealed a common pattern in endurance pursuits: hunters encounter prey, the prey initially outdistances the hunters, but after exhausting themselves, they pause to recuperate, allowing the hunters to catch up. This cycle repeats until the prey is overtaken.

Despite the common pattern, tactics varied.

“There are a fair number of cases in which these pursuits are done by teams, by relay. We also have cases where there’s an individual who will climb a hill nearby and use hand signals to indicate where the animal is going, so the person following can take shortcuts and save energy,” Winterhalder said.

This cooperation hints at a social element related to running. Winterhalder suggested that exhibiting athletic prowess could have been a way for males to showcase their value within the community, potentially boosting their social status or chances of finding mates.

In a follow-up study, Winterhalder and Morin plan to examine female participation in endurance running. Although female participation was noted in only about 3-4% of the accounts in the current study, this doesn’t necessarily mean women were not good runners.

“In a fair number of cases, we did find that there are festivals, feasts, and ritual events that involve running contests,” Winterhalder said. “In cases where we find mentions of rituals or games, the participants generally are women, men, and children.”

Additionally, recent research shows evidence that early women were also involved in hunting, challenging the notion that they were not active participants in endurance pursuits.

Winterhalder, who has a background in mathematical modeling, used these models to evaluate the value of pursuing game versus the time and energy costs.

For the latest study, he and Morin adjusted the models to consider increasing velocity during pursuits. They then compared return rates from endurance pursuit hunts to other foraging methods.

“We found that in contexts like high heat or a substrate that impedes the animal, such as crusted snow, the net return rate of food acquisition from endurance pursuits can match or exceed that of other methods of prey acquisition. The chance of pursuit failure appears to diminish, and exhausted prey are safer to approach. For early humans without ballistic weaponry, these are significant advantages," Winterhalder said.

Winterhalder hopes the research will spark more interest in understanding the origins of our running gait and why some people find running so satisfying, like the proverbial “runner’s high.”

“To run long distances, to have an evolved gait that’s uniquely imbued with stamina is unusual in the animal world,” Winterhalder said. “If that inspires you to go for a run, great.”

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