Researchers eavesdropping on wild chimpanzees determined that the primates communicate about at least two things: their favorite yummy fruits, and the trees where these fruits can be found.
Of particular interest to the chimps is the size of trees bearing the fruits that they relish most, such that the chimps yell out that information, according to a new study published in the journal Animal Behaviour.
The study is the first to find that information about tree size and available fruit amounts are included in chimp calls, in addition to assessments about food quality.
"Chimpanzees definitely have a very complex communication system that includes a variety of vocalizations, but also facial expressions and gestures," project leader Ammie Kalan of the Max Planck Institute for Evolutionary Anthropology told Discovery News.
"How much it resembles human language is still a matter of debate," she added, "but at the very least, research shows that chimpanzees use vocalizations in a sophisticated manner, taking into account their social and environmental surroundings."
Kalan and colleagues Roger Mundry and Christophe Boesch spent over 750 hours observing chimps and analyzing their food calls in the Ivory Coast's Taï Forest. The Wild Chimpanzee Foundation in West Africa is working hard to try and protect this population of chimps, which is one of the last wild populations of our primate cousins.
The researchers found that higher pitched calls were produced when the chimps encountered fruits from Nauclea trees. Smaller trees elicited still higher pitched calls, while calls associated with bigger trees with more fruit were lower in pitch.
In short, the chimps seem to "talk" a lot about Nauclea fruits!
"I never tried these fruits myself, but they do smell very good in the forest," Kalan said. "They are also quite big and easy to ingest, and we also know that they have a high energy content, which is important for wild animals."