By IANS,
Washington : It was perhaps when he stood up on his hind legs to reach for an overhanging fruit that the ancestor of primates and humans inadvertently learnt to walk upright.
And the first move on two legs was most likely a shuffle, say researchers who have developed a mathematical model that shows how humans may have walked first.
The model, created jointly by the universities of Washington and Johns Hopkins, suggests that shuffling emerged as a precursor to walking as an energy-saving method.
Metabolic energy is produced by what an animal eats, enabling it to move. But it is a limited resource, particularly for females having to take care of and feed their offspring.
“Finding food is vitally important, and an animal needs to save energy and use it efficiently,” said Patricia Kramer, of University of Washington and co-author of a recent study.
She believes it was an empty belly, along with a need to conserve energy, that prompted that early ancestor to shuffle.
“Hunger. It is always hunger,” said Kramer. “There is nothing that will get you to do something you don’t want to do other than food. That’s why we bribe animals with food to train them.”
Because of a huge gap in the fossil record that hides when humans split off from other primates, Kramer and co-author Adam Sylvester used the chimpanzee as a way of looking into the past and testing other researchers’ ideas about the origins of bipedalism.
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.
“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.
The findings of the study have been published in the latest edition of the American Journal of Physical Anthropology.