Language may be the most powerful social tool any species has evolved, we use it for physics and poetry, for gossip and jokes. Understanding the origins of language speaks to the fundamental question of what it means to be human. But what, if anything, makes human language unique? What did we need to communicate that took us beyond the systems of signals seen used by other species around us today? Many other species’ communication also contains rich exchange of nuanced information; but humans do more than broadcast information, we use it to share ideas and intentions that come into our minds with the minds of those around us. It revolutionised our understanding of non-human communication when we discovered that great apes’ use their gestures to convey meaningful information in a similar language-like way: ape gesture is essential to understanding what language is, and how human language evolved. Beyond meaning, two core features of human language are social learning and syntactic structure. These are universals, present across cultures. We all learn words and how to use them from others, leading to languages and dialects. We all use syntax; expressing different meanings by recombining words. In fact, these two particular features are common in animal communication: sperm whales learn songs from others; finches re-order notes into different songs. But, in a significant evolutionary puzzle, both appear absent in the communication of our closest great ape relatives.
The discovery of meanings in ape gesture resulted from studying ape communication under the challenging natural environments that allowed for chimpanzees to fully express their system of communication. A single study of a single group: it was the tip of the iceberg. Employing pan-African data across 25 ape and 8 human groups the Gestural Origins project tackles three major objectives.
(1) Is there cultural variation in ape gesture? We recognise that to understand human behaviour, we must study people across diverse cultures and environments. Within the 8 subspecies of African great ape there are hundreds of groups with unique cultures, inhabiting habitats as diverse as rainforest and savannah. To investigate whether or not features of human language exist in the communication of non-human great apes we must compare ape communities, including humans, within and across populations on a new, pan-African scale. We will look at how their biological inheritance, their physical environment, and their social interactions affect how apes acquire and use gestures.
(2) When apes combine signals, does it change their meaning? Moving beyond sequential structure we will look at how apes combine signals to construct meaning, and how the speed, size, and timing of gestures impacts meaning. We will use our rare access to multi-generational ape datasets.
(3) Human-ape gesture. Ape gesture research to date, has neglected the one ape that may be crucial to addressing these questions: us. With two new approaches, we will turn the tables on comparative research using ape field-methods (focal follows, playback experiments) to investigate human behaviour. We will investigate adults’ and children’s use and understanding of gestures to compare them directly to other apes.
