Chimpanzees have been observed spontaneously taking turns to complete a number puzzle in a new study conducted by researchers from the universities of Oxford and Kyoto at the Indianapolis Zoo.
This is the first time it has been demonstrated chimpanzees can cope with relatively complex cooperative behaviour without any external cues to help them coordinate their turns. Previous research has shown that the apes can work together by taking turns, although in these experiments the turn-taking was strictly controlled.
The new research, published in the journal Scientific Reports, shines a light on the evolution of turn-taking – a behaviour that forms the basis of a range of social interactions, including communication and language.
"Coordinating behaviour is an essential component of many social situations and can enable groups of individuals to jointly solve problems," said Dora Biro, co-author of the study, from Oxford's Department of Zoology. "In communication, coordination often takes the form of turn-taking, where one individual takes cues from the other to decide on the timing of their own input. This can allow for the efficient exchange of information.
"Many animals, from insects through birds to primates, take turns during certain types of communication – as do we humans during conversational exchanges. But taking repeated, coordinated turns to achieve a common goal is much less well studied outside the communication domain, despite the possibility that all such behaviours draw on the same underlying cognitive skills for turn-taking.
"Our research examined the abilities of our closest evolutionary relatives, chimpanzees, to coordinate their behaviour while completing a computerised puzzle in stages. We showed that extended bouts of turn-taking emerged spontaneously in the subjects, enabling them to solve the complex coordination problem effectively."
In a solo version of the number puzzle, the chimpanzees proved adept at touching a series of numbers in the right order – however, they had never been given a shared version of the task.
The puzzle worked like this: the numbers 1-8 were split between two touchscreens, with the pair of chimpanzees required to take turns to ensure the numbers were picked in the correct order. For example, one screen may have shown 1, 5, 7 and 8, while the other displayed 2, 3, 4 and 6. On completing the task successfully, the chimps were rewarded with small pieces of apple.
The six chimps that were involved in the study – consisting of three mother and offspring pairs – all completed the game successfully from the outset. The younger chimps were found to have quicker response times than their mothers when working in a pair. However, when they were given the individual tasks, the mothers were found to be faster, suggesting the juveniles were better at paying attention to their mothers than vice versa.
"The finding that young chimpanzees more readily took cues from their mothers when looking to take their turns reveals interesting parallels with other aspects of information transmission in chimpanzee societies," Biro said
"For example, during the learning of tool use by wild chimpanzees, we also see young individuals paying attention to older ones much more than the reverse. This kind of asymmetry has important implications for the direction of information flow – for example, how quickly new innovations in behaviour will spread through a group.
"Besides turn-taking, our task may also provide insights into abilities for cognitive perspective-taking – in other words, the capacity to improve coordination by mentally putting yourself in someone else's place. Brain studies have shown that this is a skill that musicians use while performing duets that require them to take turns. Whether our chimpanzee subjects made use of such perspective-taking capacities during solving the numerical turn-taking task is an interesting open question for future research."