March 31, 2010

Elephants Have 4-wheel Drive

Scientists said on Tuesday that elephants' legs work like a four-wheel drive vehicle, making them unique in the animal kingdom.

Their "four-leg-drive" system works by applying power independently to each limb.

All other four-legged animals are thought to use their hind legs for acceleration and their front legs for braking.

"We have developed some new techniques for looking at animal movement that may change the way that we view the locomotion of other animals," said study leader John Hutchinson, from the Royal Veterinary College in London.

"We have shown that elephant legs function in very strange and probably unique ways. We even overturned some of our own previous ideas about elephants.

"Our measurements have also provided basic data that will be useful in clinical studies of elephants, such as common lameness problems."

The researchers observed six young Asian elephants by using a three-dimensional motion capture technology.

The elephants were rigged with force-sensitive platforms as they walked different speeds along a walkway.

The team found each limb to be used for both braking and accelerating.

They reported that their legs were slightly "bouncy," especially when running at a quick pace, which made their legs two to three times less mechanically efficient than expected.

"Surprisingly, elephants use their forelimbs and hind limbs in similar braking and propulsive roles, not dividing these functions among limbs as was previously assumed or as in other quadrupeds," the scientists wrote in the journal Proceedings of the National Academy of Sciences.

"Thus, their limb function is analogous to four-wheel-drive vehicles."


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