When it comes to walking, we've got the jump on chimps

Ever feel like walking on two legs is just too much work? At day's end, when you have to stand up from your office chair, walk to the parking lot, drive home and then walk all the way up the driveway, does it all just seem like wasted effort? Well, count your blessings -- a new study has found that walking on two legs is 75% easier for you than it is for a chimpanzee.

David Raichlen and Herman Pontzer, professors at the University of Arizona and Washington University in St. Louis, respectively, investigated the costs of walking upright and on all fours in chimps (who normally do a bit of both) and humans (who don't).

Graduate student Michael Sockol trained five chimps and four humans to walk normally on a track equipped with special sensors. By measuring the forces exerted, and the changes in height of hip, knee and ankle joints, he was able to calculate the energetic "cost of locomotion." This differs among species because of unique body plans. The study found that it was just as easy for a chimp to walk on four feet as two, but that humans walking upright expend the least energy of all.

•	When it comes to walking, we've got the jump on chimps Los Angeles Times, Monday, July 16, 2007 Byline: Chelsea Martinez

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