Only an Achilles heel for Neanderthals (Image: Joson/Getty)

IF YOU think you’re no good at running, bear this in mind: you could still outrun a Neanderthal. In fact, their inferior running ability may have been why they went extinct and our ancestors did not. Appropriately enough, it all came down to their Achilles tendon.

There have long been claims that Neanderthals were weaker runners than modern humans, says David Raichlen of the University of Arizona in Tucson, but until now, there was no convincing evidence.

In runners, the tendon acts as an energy store, stretching like a spring as the foot lands then bouncing back to help lift it again. Raichlen reasoned that the more energy is stored within the tendon, the more efficient the runner.


He began by studying eight endurance runners on treadmills to find out how much energy they used at given speeds. By looking at MRI scans of their ankles, he found that the distance between a point on the heel bone just below the ankle bone, and the back of the heel bone where the Achilles tendon attaches, was proportional to the runner’s efficiency. The shorter this distance, the greater is the force applied to stretch the tendon – and the more energy is stored in it. This means that people with shorter distances are more efficient runners, using less energy to run for longer.

Raichlen then turned to Neanderthal skeletons, and found that our distant cousins’ heel bones were consistently longer than ours. Neanderthals, he concludes, would have lost a race against Homo sapiens (Journal of Human Evolution, DOI: 10.1016/j.jhevol.2010.11.002).

The evidence is convincing, says palaeoanthropologist Will Harcourt-Smith, at the City University of New York.

Raichlen thinks that, unlike our species, Neanderthals probably did not need to be good long-distance runners. H. sapiens lived on hot, dry African grasslands, where they hunted by pursuing large animals over long distances until they collapsed from heat exhaustion. In the cooler regions occupied by Neanderthals, heat exhaustion would not be a problem, so running long distances would not have helped them hunt. Instead, they took advantage of their landscape and ambushed prey.

Other palaeontologists push the analysis further. “The study hits at the crux of why Neanderthals went extinct,” says Clive Finlayson, director of the Gibraltar Museum.

John Stewart of Bournemouth University, UK, points out that H. sapiens remains tend to be associated with animals from open habitats, while Neanderthals are found with animals from closed habitats. He and Finlayson believe that when the forests of northern Europe were wiped out by the most recent ice age, Neanderthals were squeezed out of existence as well.

Archaeological evidence shows that as ice advanced from 50,000 years ago, and northern Europe’s dense forests became tundra, Neanderthals were pushed into small, isolated forest refuges in southern Europe. H. sapiens were able to adapt to hunting on the expanding European tundra. Neanderthals, says Finlayson, found themselves out of step with the environment while modern humans were perfectly suited to it. “We were in the right place at the right time,” he says.