Eavesdropping on a well-cared-for group of chimpanzees in captivity finds they use a mixture of passionate gestures, vocalizations and even sign language to get their points across with each other, and also later with humans.
Like a passionate Italian using a combination of hand movements and sounds, the chimpanzees often succeed in conveying what's on their minds, which -- in the case of chimps -- is often food, playtime and an annoyance over being ignored.
The gestures frequently happen in sequences, according to the study, which is published in the journal Animal Cognition. Co-author Mary Lee Abshire Jensvold explained how one of the studied chimps, a male named Dar, playfully forced another male, Loulis, to pay attention:
"Dar open palm slapped, a tactile gesture, on Loulis. Loulis didn't respond. Dar then used a different gesture, the foot stomp, an auditory gesture, which makes noise. Loulis responded to that gesture. This shows a persistence in communication."
Jensvold, associate director of the Chimpanzee and Human Communication Institute, and her colleagues Maureen McCarthy and Deborah Fouts studied these two chimps along with three females -- Washoe, Moja and Tatu -- at the institute. The researchers say that four of "the chimpanzees were raised in an environment like that of a deaf human child and acquired signs of ASL (American Sign Language) in this environment." When he was brought into the group, the fifth chimp, Loulis, acquired many of the language signs by copying what the other primates were doing.