In this case, whenever the chimps called out after they found a large Nauclea fruit tree, their relatives would come running. The "dinner bell" effect is itself of interest, since it demonstrates how generous these primates can be.
"Chimpanzees are incredibly social beings, and sharing food is just one way of many that individual chimpanzees can solidify relationships within their group," Kalan said, adding that chimps travel in independent parties throughout the day, and almost never with their whole group at once.
She continued, "Calling for one another at a food tree is one way that they can attract other chimpanzees in order to meet up with members of their group that they have not seen for a while."
Klaus Zuberbühler, a professor in the School of Psychology and Neuroscience at the University of St. Andrews, also studies primate communication. Zuberbühler told Discovery News, "What the authors have shown is that (chimp) call structure changes, not only in response to the food type, which was already known before, but also in relation to the size of the tree, a new finding."