Decoding Chimp communications

Have you ever wondered where our tendency to use gestures to signal our intentions to others comes from? Well, surprisingly, humans aren't the only animals to do this. Our close relatives the chimpanzees gesture to each other too, and now two scientists from St Andrews have worked out what chimps are saying, as science reporter Victoria Gill explains to Chris Smith...

Victoria -   This is about chimpanzee communication and it's not about vocalisations.  It's about the gesturing that they do.  So, this is a team from St. Andrews University up in Scotland, but they are spending time in Uganda at their field site at Budongo National Park, following two habituated groups of chimps.  Habituated, just meaning they are wild, but they're used to having human observers around and they've just followed them tirelessly for hours and hours, on months long fieldtrips, watching their interactions.  What they're saying is that they've got a distinct number of different gestures that they use to communicate.  So, things they do with their bodies, and their faces, holding their feet up, stomping their feet, moving their hands in particular ways.  And now, they've moved that further on to say in this Current Biology paper that there are 19 distinct meanings to that lexicon of 66 gestures.

Chris -   Are these chimpanzees doing this because they're habituated to people?  Do you think it's that they've learned some of this off the people who are watching them or are these clearly just chimp behaviours?

Victoria -   Well, what the researchers try to do is keep their distance and just be observers.  They don't interact with these chimps.  It's very important to them for their biology that they're studying wild behaviours.  So, what they're looking at is interactions just between the animals.  They record hours and hours of footage but the only ones that they analyse are when a chimp elicits the attention of the chimpanzee that they want to gesture to and then they make their gesture.  What the researchers have done is look at these interactions.  When the change in behaviour from the chimp that's being gestured to, seems to satisfy the chimpanzee that's doing the gesturing, that's what they're saying is the meaning.

Chris -   What sorts of things are they communicating with these gestures?

Victoria -   A few other biologist that I spoke to while I was covering this story actually have said, some of these meanings are quite vague and quite simple for such a highly sociable and very emotionally complicated and very intelligent animal.  We've only got 19 distinct meanings to 66 gestures.  So, a lot of the gestures appear to have multiple meanings, they're saying.  So, things like a parent will present its foot to its youngster to say, "Okay, you can climb on me and have a lift and I'll carry you."  Females will do this thing called 'leaf clipping' where they'll very loudly and obviously nibble and take small bites at a leaf, and that's to elicit sexual attention.  That's a very specific type of communication.  But lots of things like arm swinging and pulling a play face, basically kind of opening their mouth, the kind of big welcoming play face.  Punching even, foot stomping, even somersaulting, these very athletic tree climbing animals seem to have lots of different meanings.  So, they basically put together almost a table in this Current Biology paper of what each gesture seems to lend itself to.  So, there's a list of these 19 meanings from, "move away" "stop that" "give me that" "I want some", to "climb on me" or "I'm interested in you as a potential mate".

Chris -   Where did they get the gestures from?  Did they learn them off their parents or are these innate?  If you took these gestures to chimpanzees that don't live in this particular community in Uganda and showed the gestures to other chimp troops, would they respond similarly?  Do we think this is a universal language, if you like?

Victoria -   That's a very good question because obviously, their social connections are so tight.  These are communities of chimpanzees.  They raise their children together.  They share from watering holes.  They share food.  They're very sort of communal in their living.  And so, they're so closely connected that this might be something they learn as a specific social group.  Having said that, the researchers are studying two different social groups although they're in the same national park and potentially do cross into each other's territory.  So, they're very, very close by.  But we don't know yet if it's a universal language, just because this study comes from these specific groups at the Budongo National Park in Uganda.  So, that's a big question and another sort of challenge for field biology in that, how on Earth do you study that because you can't really look at social interactions between chimpanzees in the wild that don't know each other and would never have any other contacts.

Chris -   Do any other great apes of close relatives - bonobos are also very similar to us.  Do they do this?

Victoria -   I think bonobos, we've seen a lot of gesturing and a lot of very, very social and emotional interactions in observations of bonobos as well.  So, it's likely, yes.  We don't have this kind of lexicon breakdown, but that's just purely because nobody has written the paper for what bonobo gestures actually mean.  But there's a lot out there of observational studies of bonobos hugging each other, using kind of empathic social interactions to comfort each other and that seems to have intentional meaning as well, and they're clearly very highly intelligent.  What these researchers are saying is that actually, chimps are sort of a special case.  They're more closely related to us than they are to any of the other great apes.  So, they're an amazing case in terms of evolutionary biology to look at and find the patterns of the development of language and gesture and communication, and social interaction that will give us clues as to the evolution of our own.