Born to Run

It’s not just the title of a Bruce Springsteen song. It may also be a description of what it is to be a human being. Human beings – homo sapiens – may not be able to sprint as fast as some other mammals; having four legs gives them a decided advantage when it comes to sheer speed. But we have more endurance. We can run further, and for longer periods of time.

The science of anthropology and evolutionary biology suggests that the reason for this may be that we humans have evolved to be good long-distance runners. If, as Dr. Darwin suggests, we are descended from other primates, our bodies have evolved in ways that theirs have not. Our tree-dwelling ancestors had shorter legs, longer arms, and much shorter feet with longer toes. These features may have been perfect for swinging from limb to limb, but were not particularly suited to running.

Why would the ability to run be an evolutionary advantage?

Evolutionary biologist Daniel E. Lieberman and his associate Dennis M. Bramble suggested in a paper in Sports Medicine that humans’ choice of diet may have been a driving factor in our evolution, especially our evolution as good runners. Early humans learned to like eating meat; to eat it, they had to catch animals; to catch animals they had to hunt and chase them. All of this involved developing the ability to run well.

Early hunter-gatherers, before the advent of longer-distance weapons such as bows and arrows or slingshots, practiced “persistence hunting,” in which they literally had to chase an animal for for hours until it weakened, so they could kill it at close range with hand weapons. Being able to do this meant not only being able to run for long distances, but to do so in the intense heat of the African savannah. So humans developed a remarkable “cooling system” – a network of many sweat glands, combined with less body hair. This enables us to run for longer distances, even in high temperatures. Modern hunter-gatherers, such as tribes still living in the Australian Outback or in Africa, have been recorded as being able to run up to 100 miles per day in pursuit of their prey.

Our feet and legs evolved, too

At the same time our distant ancestors were shedding body hair and developing more efficient cooling systems, they were growing longer legs and shorter toes. While the longer toes of other primates may have been better for climbing trees and swinging from limb to limb, they weren’t very good at running. Shorter toes make running more efficient; an increase in toe length of 20% doesn’t increase the effort of running 20%, it doubles the effort required to run. The fact that our big toes point straight ahead instead of off to one side like other primates’ big toes is also seen as an indication that our feet evolved into a form more suited to running.

Longer legs, with their correspondingly longer ligaments and tendons, are also crucial to running. Our primate relatives don’t have them. Similarly the largest muscle in the human body – the gluteus maximus – is a muscle that seems to have been primarily designed for running. It is barely used when you walk, but is one of the most important muscles used when we run.

Even the fact that we have narrower waists and a midsection that can easily turn is an evolutionary advantage over other primates when it comes to running, because this enables us to turn more quickly when following prey over a zig-zag course. It also allows us to swing our arms as we run, which provides a better sense of balance.

All of this is conjecture, of course, but the evidence of evolutionary changes that occurred in homo sapiens but did not occur in our cousins does seem to indicate that compared to them we were “born to run.” Or at the very least we evolved to run.

Remember this next time you go out for a jog. Even if you’re not in the best of shape yet, take some comfort in the fact that even the most fit chimpanzee or ape or gorilla on earth probably wouldn’t be able to keep up with you.

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