Chimpanzees have a pretty complex language of gestures for communicating, including stomping their feet to say "stop that," showing the sole of a foot for "climb on me," and chewing on a leaf to call for sexual attention, according to a new dictionary of basic chimp language compiled by researchers in Scotland.
Anthropologists Dr. Catherine Hobaiter and Professor Richard Byrne of the University of St. Andrew in Scotland used a method called focal behavior sampling to analyze more than 4,500 gestures in 3,400 interactions made between 80 chimps in the Sonzo community in Uganda's Bondongo Forest to come up with 66 gestures used for 19 different meanings. All gestures were recorded on film using a Sony Handycam between 2007 and 2009. Their findings were recently published in the Current Biology journal.
"There is abundant evidence that chimpanzees and other apes gesture with purpose," says Prof. Byrne. "Apes target their gestures to particular individuals, choosing appropriate gestures according to whether the other is looking or not - they stop gesturing when they get the result they want. And otherwise they keep going, trying out alternative gestures or other tactics altogether."
Some of the gestures were used to communicate simple meanings, such as "move away" for punching the ground or "get object" for stroking the mouth. Other gestures, like many words in the English language, have multiple meanings. Grasping another chimp sometimes means "climb on me," but it can also indicate "stop" or even "go away." Or when a chimp slaps one object against another, it could mean it either wants another chimp to follow or to move closer.
What is notable, however, is that the gestures used to communicate different meanings remained the same "irrespective of who uses them," says Dr. Hobaiter. Seventeen out of all 19 meanings extracted by the researchers were meant for initiating social contact, such as "travel with me," "climb on you," and "let's get frisky."
It has long been known that chimpanzees use gestures to communicate with one another, but this is the first time humans have attempted to decipher the meaning of these gestures and compile them into the first dictionary of chimpanzee language.
In a separate study also published in Current Biology, Switzerland's University of Neuchatel primatologists Emilie Genty and Klaus Zuberbuhler discovered that a specific gesture used by bonobos is meant to initiate mating. The complicated gesture involves stretching one arm towards the desired partner, sweeping it inwards and twirling the wrist to turn the downward-facing palm upside.
The researchers recorded 1,080 sexual gestures made by a total of 18 males and 17 females in two bonobo communities living in the Lola Ya sanctuary in Congo.
