Even at fast speeds, it might seem to the casual observer that elephants don't run. Their footfall pattern remains the same as that in walking, and never do all four feet leave the ground at the same time - a hallmark of running. But biomechanists are finding that an elephant's center of mass appears to bounce at high speeds. If that turns out to be true, an elephant's gait meets the biomechanical definition of running.

Biomechanists have dubbed this gait "Groucho running" after the silly, crouched walk of Groucho Marx. They say the elephants seem to bend their limbs slightly in order to move their bodies more smoothly. This research may provide insight into the biomechanical tricks that help large animals, from extinct dinosaurs to obese people, overcome the physical forces that restrict their motion.

"We do find evidence that elephants run in a sense," said first author John Hutchinson, a Stanford postdoctoral research fellow in the Department of Mechanical Engineering. "It's an intermediate sort of gait, but it looks like what we biomechanically would call running. They don't leave the ground, which is the classical definition, but they do seem to bounce, which is the biomechanical definition."

Last year Hutchinson co-authored another Nature paper that used a computer model of physical forces to show that Tyrannosaurus rex probably was too big to run quickly. For his recent paper, he teamed up with Dan Famini, a veterinary student at the University of California-Davis; Richard Lair, an adviser and international relations director at the Thai Elephant Conservation Center; and Rodger Kram, an associate professor of kinesiology and applied physiolo
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Contact: Dawn Levy
dawnlevy@stanford.edu
650-725-1944
Stanford University
2-Apr-2003