Gestural communication plays an essential role in humans and other primates, allowing individuals to reliably transmit information to other group members. In the last decades, there have been important advances in the study of primate gestural communication, yet there are still many aspects that we do not fully understand. For instance, how do gestures emerge through primate development, and which role has social experience in shaping individual gestural repertoires? Do social processes affect the complexity and effectiveness of gestural communication, and are there differences between great apes and other primate species? Does gestural communication really have the flexibility that makes it a possible precursor of human language, as some researchers propose, and can primates combine gestures to transmit novel meaning? In this plenary, we will address these issues and present some of the work that we have conducted at our facilities on these topics, highlighting possible avenues for future research.

SIMPLE TRICKS. Insects share many basic cognitive and perceptual mechanisms with us. This means that it should be possible to fool ants using the same cognitive tricks which work on us. For example, many retailers use ‘bundling’ to manipulate us into buying more. This trick involves putting many small prices together into one total, which is then perceived as smaller than the sum of all the small prices separately. We tested this bundling effect on ants, and found that ants indeed like rewards less if the cost of reaching them was split over three stages, rather than all paid in one go. However, while apparent liking was affected, subsequent choice was not. This may tell us something fundamental about how travel costs are uniquely perceived by ants.

SMART ANTS. When travelling, ants often encounter other ants on the trail. These nestmates are a valuable source of information. For example, encountering many ants returning from a limited food source may imply that this food source should be avoided. Amazingly, outgoing ants do strongly respond to meeting returning ants, but only if the food source they encountered had a limited capacity. The ants seem to infer that one feeder might be overexploited when they will arrive, even though they have never experienced this feeder as over-exploited. This suggests a truly unexpected level of cognitive sophistication.