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Gestural Origins: Linguistic Features of pan-African Ape Communication

Periodic Reporting for period 1 - GESTURALORIGINS (Gestural Origins: Linguistic Features of pan-African Ape Communication)

Reporting period: 2019-03-01 to 2020-08-31

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 17 ape and 9 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.
Over the first reporting period the project has achieved several significant milestones:

1. We have set up new data collection protocols and direct-in-video coding methods that will allow us to collect data across all species - including humans - living in a wide range of environments in a similar way. To date, most gestural research has focused on chimpanzees, here we used pilot data collection across other species, including gorillas, bonobos, and humans, to make sure we could develop a truly pan-African ape approach. Doing so is not straightforward, a particular behaviour in a chimpanzee may represent aggression, while the same behaviour in a gorilla may represent something very different. It takes substantial work to be able to set up and verify a universal approach. Now that we have done so we are developing it as an open-access resource to allow for these methods to be used by researchers around the world.

2. We have set up datasets for 6 of our 8 subspecies of ape, including communities from all the four major species: chimpanzees, gorillas, bonobos, and humans. We've started new data collection with 9 communities of apes, as well as the pilot work for several new human projects and populations. Our initial data collection has been going extremely well, with more data than originally planned available from our early field seasons.

3. Three of our students are now fully-trained experienced coders, and we've just welcomed our next cohort of staff and students who'll be expanding the range of ape subspecies and locations even further.

4. You can find our project website at which is where we'll also be hosting the citizen science experiments that form a key part of our research on human understanding of ape gesture. Researchers can go there to request access to collaborate with our video archives, or visit where we host all of our code and, in the future, where we'll also be sharing data sets.

5. All apes are vulnerable to Covid19, and to ensure the safety of the human and non-human primate communities we work with we have put all in-person data collection on hold. Fortunately we are able to continue working from our large video archives, and have set up several new collaborations that give us access to datasets from new and planned locations. We've recently started to explore machine learning approaches to automate locating and coding communication, improving our efficiency and reliability.
Exploring the gestural communication of apes from different subspecies is not simply about building big data sets that give us more details about the questions we can ask by studying one or two groups. There are some questions that you can only answer at scale. We could not describe human language by only collecting data in St Andrews, Addis Ababa, or Shanghai - we need to understand the full range of ways in which it is expressed across cultures to see the human universals. Just like humans, the communities of other ape species can be small or large, egalitarian or despotic, cohesive or dispersed, live in wide open savannah or in dense rainforest. Each one will have its own unique social and physical environment, and moreover other apes also have their own unique culture. We need to be able to put all of these diverse pieces of the puzzle together to be able to see the road map along which human language evolved.

Gestural Origins gives us that road map, not only can we explore the similarities and differences between human language and ape gesture, but by building a rich detailed picture we can make new predictions about the communication of groups as yet unstudied - a robust way in which to test hypotheses about language evolution. Building a fully accessible video data archive will allow us to address current barriers present to research on wild ape behaviour, as well as providing an invaluable data-ark for species’ in urgent conservation crisis. To achieve this we are building new data collection and analysis tools that will provide an open-access framework for exploring questions of comparative communication across diverse species of primates and beyond.