Were humans built to run long distances? A popular theory faces tough questions.
No other primate can run long distances, and we sweat, steady our heads and store energy in springy tendons in ways that seem made for it. The endurance running hypothesis says early humans ran prey to exhaustion. Critics argue most of those traits evolved for walking instead.
The endurance running hypothesis proposes that running long distances shaped the human body more than any other behaviour. Its strongest version claims running is the only known behaviour that explains why the bodies of our genus, Homo, differ so much from those of apes and australopithecines. Proponents suggest that from roughly 1.9 million years ago, early humans used it for persistence hunting, chasing large animals in the heat until they overheated, and to reach carcasses ahead of other scavengers.
Supporters point to a long list of features. Humans shed heat by sweating, including from the scalp and face, while large four-legged prey struggle to stay cool on a long chase. We have a ligament at the back of the neck and a flatter face that help keep the head steady, shoulders that can turn without turning the head, a springy Achilles tendon, a stiff arched foot, long legs and large buttock muscles. The palaeontologist Daniel Lieberman has argued that several of these make little sense for walking alone. Related research found that people who have always run barefoot tend to land towards the front of the foot rather than the heel, with gentler impact forces.
The critics have plenty to say. Longer legs and an arched foot appear to have been present already in Australopithecus, which suggests they evolved for efficient walking, with better running as a by-product. The way the list of 'running traits' was chosen has been questioned, and most have never been tested for their effect on walking versus running. Measurements show the gluteus maximus works far harder in sprinting, jumping and punching than in steady running, pointing to powerful movement rather than endurance. One model suggests scavengers would have reached a carcass within about 30 minutes anyway, removing much of the advantage of running long distances to it.
So the question remains open. Humans really are unusual, and good at covering long distances on foot in the heat. Whether that talent drove our evolution, or was a happy side effect of becoming excellent walkers, is still being argued over, fossil by fossil.
Source: Wikipedia — Endurance running hypothesis · Text summarised from Wikipedia (CC BY-SA 4.0)
