Chimpanzees use their hands to say "follow me," "stop that" or "take this," according to new research seeking to translate the sophisticated messages flowing back and forth.
Previous research had revealed that our nearest genetic relatives use gestures to communicate, prompting questions over whether the communication systems shared ancestry with the origins of human language.
The new study, published Thursday in the US journal Current Biology, created the first ever chimpanzee dictionary of sorts, deciphering just what the apes were saying to each other.
The researchers said the chimpanzee gestures -- they decoded 66 in total -- can be used in isolation or several can be strung together to create more complex exchanges.
And, importantly, the meaning remained consistent, regardless of which ape was making the gestures.
The messages ranged from "simple requests associated with just a few gestures to broader social negotiation associated with a wider range of gesture types," said the authors from the University of St Andrews in Scotland.
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."