Humans took to walking on two legs or developed bipedalism simply because this process was more energy efficient, according to a new study appearing in the online edition of the Proceedings of the National Academy of Sciences.
The article titled, "Chimpanzee locomotor energetics and the origin of human bipedalism”, is due to appear in the print issue on July 24. Human bipedalism is an issue of much significance among anthropologists. The fact that this is the only discernable difference between apes and man as far as physical mannerisms are concerned has caused much debate.
Researchers have theorized that bipedalism used less energy and thus helped man gain some evolutionary advantage because it decreased the effort involved in foraging. In the present study researchers analyzed the differences between bipedalism and quadrupedalism by comparing the gait of four adult humans and chimpanzees that were trained to walk quadrupedally and bipedally. A treadmill was used for this purpose.
Researchers found that humans expended only one quarter of the energy by walking on two legs as compared to the chimps that used four legs.
"We were able to tie the energetic cost in chimps to their anatomy," said David Raichlen, of the University of Arizona. "We were able to show exactly why certain individuals were able to walk bipedally more cheaply than others, and we did that with biomechanical modeling."
