Why We Walk

Science Daily:

A new study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knucklewalking.

David Raichlen, an assistant professor of anthropology at The University of Arizona, conducted the study with Michael Sockol from the University of California, Davis, who was the lead author of the paper, and Herman Pontzer from Washington University in St. Louis.