Washington, May 30 : When babies learn to walk, they usually start covering short distances by shuffling. Now, a new research has suggested that our ancestors did the same before they learnt to walk - as a way of saving metabolic energy.
The suggestion comes from researchers from the University of Washington and Johns Hopkins University who have developed a mathematical model for the same.
Patricia Kramer, a UW research assistant professor of anthropology and co-author of the study, used chimpanzee as a way of looking into the past and testing other researchers' ideas about the development of bipedal behaviour - or walking on two feet.
Chimpanzees are humans' closest relatives. They basically walk on all fours, partially resting their weight on the knuckles of their hands.
"A chimp's body plan is very much like that of a primitive ape, and our last common ancestor probably had a body like that of a chimp. Modern humans are different with long legs and a big head. So chimps are a good place to start," Kramer said.
Using the model they devised, the researchers calculated it would not be metabolically efficient for a chimp to use bipedalism for distances greater than about 50 feet.
However, it would be efficient and that most shuffling would occur for distances less than 30 feet.
Besides this, walking on two feet would be used most frequently for distances less than three feet.
"These are predictions other people can test. You should rarely, if ever, see a chimp-walking upright at longer distances. The flipside of this is if a chimp is going a short distance returning to all fours is not going to happen. You can see this in human babies learning to walk. If they are going between a couch and a coffee table they are up on their feet. But if they are going a longer distance, they go down and crawl," she said.
"We think metabolic energy is extremely important and we have only touched the surface of the information we can get with this work. The model allows people to plug in the body characteristics of any primate so a researcher can change the parameters for a specific species," she added.