麻豆传媒

A couple of months ago, Daniel Lieberman set out on the race of a lifetime. A 25-mile slog in the Arizona heat, climbing a mountain more than 2000 metres tall. To top it all, 53 of his competitors had four legs. This was the .

Lieberman, by his own admission not a great runner, outran all but 13 horses 鈥� and so could you.

Lieberman , and part of his work over the past 15 years has focused on a unique set of adaptations that suggest modern humans evolved not just to walk, but to run long distances.

One is our cooling equipment. 鈥淭he fact we have sweat glands all over our body and we鈥檝e lost our fur enables us to dump heat extremely effectively,鈥� says Lieberman. This is crucial when running for long periods. It helps to explain why animals struggle to beat us in the heat, even though sled dogs can run more than 100 kilometres a day pulling humans in cold climates. Hence also Lieberman鈥檚 success in Arizona. 鈥淭he hotter it is, the better humans are able to run compared with horses,鈥� he says.

Then there are adaptations that offset our clumsy, inefficient bipedal frames. Short toes and large gluteal muscles assist with balance and stability. The Achilles tendon and other springs in the feet and legs help us to store and release energy. We tend to have a high proportion of slow-twitch muscle fibres, which produce less power but take longer to tire than the short burst, fast-twitch fibres needed for sprinting.

The nuchal ligament at the base of the skull also helps to keep our heads, and therefore our gaze, steady when we run. Other decent runners such as dogs and horses have one, but they鈥檙e not found in poor runners such as pigs and non-human primates or early hominids like Australopithecus. Many of these adaptations are specific to running, suggesting we鈥檙e not just good at it because we are good walkers.

One theory is that we began running as scavengers, where an ability to outrun other carnivores to reach fresh meat was to our advantage. As we improved, we became better hunters, able to track and outrun our prey over large distances before we had spears and arrows. This all helped to provide us with the extra protein we needed to acquire our greatest advantage: a bigger brain. 鈥淭he features that we see in the fossil record that are involved in running appear about when we start to see evidence for hunting. And soon thereafter their brains start to get bigger,鈥� says Lieberman.

So can you unleash your inner marathon runner? In a word, yes. Genetics is important but training is key, says sports scientist . You鈥檒l need stronger leg and bum muscles, to be sure, but you can get these simply by starting to run. You will find it hard to increase the proportion of slow-twitch muscle fibres you have, but if you find yourself flagging, take your time and take comfort in the fact we evolved to jog, rather than sprint, over the finish line. 鈥淢illions of people run marathons and people tell us we are crazy,鈥� says Lieberman. 鈥淎ctually, it鈥檚 part of who we are.鈥�

This article appeared in print under the headline 鈥淵ou are鈥� an athlete鈥�