image: The shape of a fossil femur (thigh bone, center) from Kenya shows that our early ancestors were already adapted to upright walking by 6 million years ago, and suggests that this early form of two-legged walking persisted until 2 million years ago when major changes in hip anatomy occured in Homo erectus. This image relates to an article that appeared in the March 21, 2008 issue of Science , published by AAAS. The study, by Dr. Brian Richmond and colleagues at George Washington University in Washington, DC, was titled "Orrorin tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism." view more
Credit: Image courtesy of John Gurche and Brian Richmond