Could animals speak?

Here on the radio we certainly enjoy talking. And a new piece of research this week has revealed the parts of the brain that may have been key to this behaviour evolving. Georgia Mills has been investigating...

Georgia - Who hasn’t wanted to confer with cockatoos, banter with antelopes, or rabbit on at rabbits. But can any animals talk back?

Jacob - It kinda depends on what we mean by "talking"...

Georgia - That’s Dr Jacob Dunn, Director of the Behavioural Research Group at Anglia Ruskin University.

Jacob - There are other animals that can mimic speech sounds - famously a lot of birds do this like parrots, and budgies, and so on. They can make lots of different sounds; whether we think that cognitively they're using language in the same way that we are is a bit of a different question. But certainly, they can make complex speech sounds which sound very much like they’re talking.

Georgia - This mimicking has even been seen to some extent in seals, elephants, and killer whales. So what about our closest cousins - the primates?

Jacob - Well, this is where it gets really interesting, because the apes and the other primates, one would think, because they’re closely related to us and do lots of very clever things like using tools, one would think that they would have very advanced communication similar to our own. But when it comes to vocal communication, they seem to be really quite limited and they don’t use complex vocalisations in any similar way to the way that we use speech.

Georgia - So something quite distantly related like a parrot can mimic human speech and demand crackers, yet our closest relatives can’t despite the fact that all things point to them having a very similar vocal anatomy. So what’s going on?

Jacob - What people have said for a long time; in fact Darwin said this, he said “perhaps the brain is much more important in this regard.” What we went out to do was the first sort of large-scale comparative study looking at non-human primates, which make a range of different sounds, and saying okay, well they don’t make many different sounds, but there is a variation across different primate species in how many sounds they produce. So we carried out an analysis trying to compare that variation to brain architecture.

Georgia - How did you do that and what did you find?

Jacob - The brain data came from published data. There are large brain collections in different places around the world, and the information about the size of the brain, the weight of the brain, and then the various different structures within the brain are calculated through histology. So what that really means is that you’ve got, a bit like in a delicatessen in a supermarket, you put your brain through a slicer. You’ve got lots of very very thin slices of pastrami, and then you’re able to take images of each of these slices and, eventually, recreate a 3D model of the brain.

Georgia - Crucially you then don’t eat it afterwards!

Jacob - Then you don’t eat it afterwards. You’d probably get quite sick if you did! We took this data on the size of different structures of the brain across these different primate species and related it to the number of different vocalisations that they produce.

Georgia - What did you find?

Jacob - We found a very strong positive correlation between the number of different sounds primates produce and the relative size of their cortical association areas. The cortical association areas are important information centres in the brain. They receive the sensory input and they are a bit like a computer that decides what to do with that. We also went on to look at some other areas of the brain. What we found was that the hypoglossal nucleus, which is this little structure in the brain stem from which the nerve comes out and innervates the tongue, was found to be significantly bigger in apes than in other primates, as were the cortical association areas. So this might tell us a little bit about how, through human and hominin evolution, we evolved with time to grow smarter brains but also how that might have co-evolved with this particular part of the brain, which is innervating the tongue. And that might tell us something about how, eventually, in our primate ancestors, we achieved better control over the vocal apparatus as our brain was changing.

Georgia - But forget about finding out the answers to crucial questions on the origins of humanity. When are we going to get talking monkeys?

Jacob - The recent literature - a really great paper came out saying that the monkey vocal tract is "speech ready". What they argue is that the vocal tract of the macaque, which they looked at, is capable of moving in all the ways to be able to produce the key vowel sounds which are important for human speech. And therefore, if we were to stick a human brain on top of a macaque larynx, it ought to be able to speak!

Georgia - Monkey butlers.

Jacob - Exactly. And therefore, in the future, who knows exactly how this is all going to play out but, one way or another, there may be new techniques to be able to fiddle around with the brains of bio-med primates, which I would not be on board with I have to say, to begin to get them to produce language...