Do primates have their own language?

Chris Smith put this question from Dave on Twitter to primate expert Jacob Dunn from Anglia Ruskin Univeristy.

Jacob - So that's a really big question. And it sort of gets really at the nub of what I'm interested in. Language is a very complicated thing, it's something that we just do very naturally and learn to do with time. The word I guess refers to this sort of complex system of multiple parts of grammar and words that we combine together to form sentences and ideas and so on. Language of course doesn't only come in this sort of spoken form that we're using now it's also written and sign language, Braille and so on as various forms of language. And of course there are languages as well. So the word is a complicated idea.

灵长类动物有拉nguage? Yes because humans are primates and we use language and for many thousands of years other hominin relatives that are relatives of humans would have also been very likely to have been using language. So Neanderthals and Denisovans and the hobbits from Indonesia and so on and even for quite a long time before that it's quite likely that other species like Homo erectus were using fairly complicated language at least quite similar to what we use now.

Chris - I've seen the the brain casts the so-called endo-casts of some of the skulls of some of the aforementioned early human ancestors that you mentioned and specifically they have a bulge in the part of the brain on the left hand side where modern humans have a bulge which is our language center. And paleoanthropologists use this as an argument that probably language was evolving because the brain seems to show the same sort of specialization.

Jacob - Yeah there are lots of sort of quite crude markers of what might represent language in these hominins for which we've only got a few bones. I suspect the brain’s quite a bit more complicated than just whether on the outside of the brain you have a little bulge.

Chris - Dogs have that as well don't they? If you look at a dog's brain it's also slightly asymmetric and we think that's why dogs are quite good at interpreting human language possibly.

Stuart - It is. I would probably argue it's more to do with the tone of it. So when somebody walks in and says “I've spoken to him [the dog] and you knew he did wrong” it was probably the tone of voice used, it wasn't the word used. So I'd probably be a little bit cautious about saying that a lump on the brain means that they know what they're talking about.

Chris - But the dog in the Guinness Book of Records was called Rico? Ringo? and it had a 300 word vocabulary. It was a collie, died now unfortunately. But it had this extraordinary ability you might remember they did the study where you could show it one of its toys which it knew the name for. And you could put a whole bunch of these toys that it knew the name for in the next room and then one new toy that it did not know the name for never seen before and you can say to it go and get the x from next door and the x it knew it didn't know that name so it would retrieve the toy it didn’t know the name for. So it clearly did understand how to engage with and process language.

Stuart - Yeah sure. No I think there's certainly ways in which they can make those associations it's a certain amount of conditioning. But yes.

Chris - Jason?

Jason - I was just wondering if it's a collie that has a 300 word vocabulary, how many of those words are synonyms for food?

Chris - Oh I'd say almost all of them! But back to you Jacob...

Jacob - Yeah, back to primates and the sounds that they make and if that's language, basically it depends on whether people think this is a qualitative or a quantitative difference. There are some aspects of what primates say that we might think of as sort of quite simple language. Several primate species have been known to use “words” in inverted commas that refer to really specific things in their environment. For example the predators or food and they only use those words in those exact contexts you know when they see a leopard or an eagle or something, and they use that word only then.

所以他们有这种相当于我们call semantics in language sort of labelling things referring to things in the world. And the other aspect of primate communication which represents something which is similar to something linguistic, is that they also combine words what we call syntax in human language. So they say A and B together and that means something different from a and b independently. And so they’re on a sort of very different end of the scale the question is whether that's a continuum and we’re on the language end and then on the simple end and they use proto language or whether it's something completely different and that's quite subjective.