My name is Kirsty Graham and I study how bonobos use gestures to communicate. I’ve always been interested in languages, especially imagining how human language evolved in the first place. I like that it’s possible to study animal communication not only to discover the cool ways that animals communicate, but to compare them to how humans communicate. My current research focuses on how bonobos use gestures, what the gestures mean, and why they might have multiple meanings.

 

When you’re talking on the phone, think about what your hands are doing. Even though the person on the other end of the line can’t see you, chances are you’re still making gestures. Gestures often accompany speech and are an important part of how we communicate. It’s no wonder that some researchers think that human language might have originated from gestures. Great apes (a family that includes chimpanzees, gorillas, orang-utans, and bonobos) also use gestures to communicate. I study bonobo gestures by filming their behaviour at the Wamba research station in the Democratic Republic of Congo.

Bonobos use gestures intentionally, aiming to change the behaviour of whoever they’re gesturing to. In fact, they use a greater variety of gesture types than vocal calls. We know quite a lot about how great apes use or express gestures, but we know less about how they understand them. When a bonobo uses a gesture, I can assume that that bonobo knows this gesture, and so I list that gesture in their gesture vocabulary, or “expressed repertoire”. This is where all other great ape researchers have stopped. But I’m interested in what happens with the bonobo that sees the gesture. Do only some individuals use a gesture and only some individuals receive and understand it?

I thought maybe gestures that are used more often are more likely to be expressed and understood. Imagine human language: words like “duck” are used quite often and many people both use and understand them. But the more specific name “mallard” is used a lot less often, even though most people understand it. The same was true for bonobo communication – the more popular a gesture, the more individuals both expressed and understood it.
The Duck-Mallard difference is important for another reason. Even if you’ve never said the word “mallard” out loud, it’s still in your vocabulary if you can understand it. Now that we are able to tell which gestures a bonobo understands, we can include those rarer mallard-like gestures in their vocabulary too.

I found that the community of bonobos in Wamba use 67 different gesture types. But most of the individuals express only a few of these types (13 gesture types on average) even though they understand more. If we include the gesture types that they understand, an individual’s vocabulary grows to 17 gesture types! Most interestingly, there is no difference between male, female and young bonobos; they all use and understand the same gestures!  

 

What this all means is that bonobos use their gestural repertoire to communicate with each other – all individuals, regardless of age or sex, have the potential to use all gesture types. That’s a lot like language, wherein all humans can, in principle, use any word they want. Gestures clearly share some characteristics with language, and it will be very exciting in the future to see just how gestures and language co-evolved.

 

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Kirsty Graham, PhD candidate

 

 

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Alina Loth, PhD candidate