01 June 2007
Vol 316, Issue 5829

About The Cover

Cover image expansion

COVER An orangutan (Pongo abelii) from Sumatra, Indonesia, in an upright posture. Orangutans, a more distant relative of humans than chimps or gorillas, move in a bipedal fashion on small flexible branches. Human bipedalism may thus reflect selection of a behavior that was present in the common great ape ancestor. See page 1328. Photo: Art Wolfe/Getty Images