It’s kept us awake every night for years: when elephants charge, are they running or walking?
The conundrum got too much for John Hutchinson from the Royal Veterinary College, who resolved to find the answer.
At first glance, fast-moving elephants look as if they are walking, he says. But closer analysis of their footfall patterns suggested that, when they’re in a hurry, their front legs walk while their hind legs trot.
Bewildered, Hutchinson threw himself on the mercy of Norman Heglund from the Université catholique de Louvain, Belgium, who realised that the only answer was to measure the forces exerted on the animals by the ground as they move.
To do this, Heglund constructed and calibrated an 8m long platform from sixteen 1m2 force plates. They crated them up, along with cameras and computers, and shipped the lot from Belgium to the Elephant Conservation Centre in Thailand, where they put it all together. They were on a roll.
Urged on by their trusty mahouts, 34 assorted elephants crossed the force platform at speeds ranging from a stroll to a charge. Based on the force measurements, the team found that the elephant’s cost of transport is 1/3 that of a human and 1/30 that of a mouse.
Next, the team calculated the way that each animal recycles potential energy into kinetic energy to find out whether they run. They found that as the elephants moved faster, the kinetic and potential energy plots shifted to look like those of runners.
However, when the team analysed the movements of the elephant’s centre of mass, they could see that it was more or less constant as the animal shifted its weight from one side to the other, but bobbed down and up like a runner’s during the second half of the stride.
So, after all that, the answer?
“It really depends on your definition of “run”,’ says Heglund.
He explains all, at his website. Google it!