The Genetic Factor

Geneticist Sean Carroll looks at the likely underpinnings of the handwalkers' condition. The Family and Me

Working with the Ulas family deeply affected psychologist Defne Aruoba.

Origins of Bipedalism

Explore hypotheses for why we stand up, choose your favorite, then hear what paleoanthropologist Donald Johanson thinks. Compare the Skeletons

The bones of chimps, early human ancestors, and modern people reveal what it takes for us to walk upright.