New research published in the journal Nature Communications has found that chimpanzees can use gestures to coordinate actions in pursuit of a specific goal.
A female chimpanzee with two juveniles at Kibale National Park, Uganda. Image credit: Julie Rushmore / UGA.
In this study, scientists led by Dr Charles Menzel of Georgia State University examined how two language-trained chimpanzees (Pan troglodytes) communicated with a researcher to find food.
Both primates, named Panzee (19 year old female) and Sherman (31 year old male), had been reared from an early age by human parents and given extensive exposure to lexigrams, which they use in everyday interactions with humans. They had been involved in cognitive research in topics such as language acquisition, long-term memory and numerical competence.
At the Georgia State University’s Language Research Center, Dr Menzel with colleagues devised a task that demanded coordination among the chimpanzees and a human to find food that had been hidden at various distances and locations.
The researcher did not know where the food was hidden and searched by repeatedly pointing towards potential target locations, watching the chimpanzee for feedback and, based on this feedback, varying the pointing direction, pointing distance and their own distance to the target location.
“The design of the experiment with the chimpanzee-as-director created new ways to study the primate,” Dr Menzel said.
“It allows the chimpanzees to communicate information in the manner of their choosing, but also requires them to initiate and to persist in communication.”
Panzee and Sherman used gestures to recruit the assistance of an uninformed experimenter and to direct the experimenter to the hidden food 10 or more meters away. They increased the rate of non-indicative gestures when the experimenter approached the location of the hidden food. Panzee also elaborated her gestures in relation to the experimenter’s pointing, which enabled her to find food more effectively than Sherman.
“Because of the openness of this paradigm, the findings illustrate the high level of intentionality chimpanzees are capable of, including their use of directional gestures,” Dr Menzel explained.
“This study adds to our understanding of how well chimpanzees can remember and communicate about their environment.”
Lead author Dr Anna Roberts from the University of Chester added: “the use of gestures to coordinate joint activities such as finding food may have been an important building block in the evolution of language.”
“Previous findings in both wild and captive chimpanzees have indicated flexibility in their gestural production, but the more complex coordination task used here demonstrates the considerable cognitive abilities that underpin chimpanzee communication,” said co-author Dr Sarah-Jane Vick of the University of Stirling, UK.
Dr Sam Roberts, also from the University of Chester, noted: “this flexible use of pointing, taking into account both the location of the food and the actions of the experimenter, has not been observed in chimpanzees before.”
______
Anna Ilona Roberts et al. 2014. Chimpanzees modify intentional gestures to coordinate a search for hidden food. Nature Communications 5, article number: 3088; doi: 10.1038/ncomms4088
