The researchers studied more than 4,500 gestures within more than 3,400 interactions, all captured on film in Uganda between 2007 and 2009. They determined that when a mother shows the sole of her foot to her baby, she means "climb on me. Touching the arm of another means "scratch me" and chewing leaves calls for sexual attention. The researchers said their observations revealed unambiguous links between some gestures and outcomes -- like the seductive message of leaf-chewing. Others seemed to convey more than one idea, like grasping another chimp, which sometimes seemed to indicate "stop," and other times "climb on me" or even "go away.