How changing scenery changed our ancestor's language

Scientists from the Universities of Warwick and Durham say they have discovered how a shift in our ancestors' habitat may have prompted early humans to change their vocalisations and ensuing language. Charlotte Gannon is a language psychologist and lead author on the paper.

Charlotte - 17 million years ago, we started to have this big continental tectonic movement. So our geographical landscape completely changed. We moved from living in this dense forests-like world to much more open landscapes. And as a result of all these climate changes, we then started to have all of these different evolutions within our hominid line. So we were really interested in looking at that period when we came down from the trees and started living in these more open landscapes.

Will - So how do you take the tools and things that we have nowadays and turn back the clock and try and recreate something that was going on millions of years ago?

Charlotte - So we use two vocalisations that orangutans make. So orangutans are really important. They're the only arboreal great ape. They're still spending the majority of their time up in the trees. They also make many different vocalisations, but two in particular that we were really interested in were called the kiss squeak and the grumph. So kiss squeaks are what we refer to as consonant-like calls, and grumphs we refer to them as vowel-like calls. So when we make a consonant-like noise, so say a P or a B or a T, we are manipulating the tongue and the mouth and the jaw. And when we make an A-E-I-O-U, we are not using any of that manipulation. We're just making the sounds. And when an orangutan makes a kiss squeak, they follow a very similar pattern of mouth manipulation that we do when we make the consonants. And when they make the grump, again, like the vowels, there is none of this manipulation.

Charlotte - So we're able to kind of use them almost a bit like really early consonant and vowel-like sounds. So we were able to take recordings that we'd had previously and we were able to play these across the Savannah in South Africa.

Will - And what did you find when you played these vocalisations out?

Charlotte - We found that the consonants actually travelled much further than the vowels, which was really interesting. So the kiss squeak noise that the orangutans were making were still about 80% audible at 400 metres, whereas the vowel-like or the grumph calls, they were actually dropping off around 125 metres.

Will - I guess this is a question more acoustics than psychology, but do we have any idea why that might be?

Charlotte - Interestingly, we initially expected the opposite. So the kiss squeak calls are a higher frequency, and the grumph light calls are a low frequency. We would actually expect, from what we know about our frequencies and our law of sound propagation, that the lower frequency sound should have travelled a lot further. And really interestingly, I think it does highlight the importance of actually using the living great apes that we've got. Because if we ran this through a simulator, we would've actually expected the opposite. And what we're looking at could actually be more of an indication as to what happened to our early ancestors and maybe also how differently our vocalisations will have been back in the day.

Will - The idea then is that we shifted to a more consonant dominated vocalisations because it allowed us to communicate better and over further distances. What kind of advantages do you think that would've brought?

Charlotte - If you look upon, not just how far the actual vocalisations you're travelling, but that's how far the message will have been travelling. So if we could have been relying on these consonant light noises to travel much further, then the information was travelling further. It will have helped our social bonding, it will have helped our cognition, it will have helped strengthen our society and helped move our evolution further.

Will - The more I read about it, the more that this seems like because language is so fundamental to our cognitive development, that this could be one of the most important shifts towards us becoming the species we are today.

Charlotte - Language in particular is really hard to study because it doesn't fossilise. We can always carbon date anything we find, but language is just this great big mystery. We know we have it, and we know we're the only animal in the entire world that has it in such a way that we do. A lot of different areas of research will come back to language. You can look at child development, you can look at psychiatry, everything. A lot of it can always be linked back to language, language therapy, all of these things. And yet there's still this big great mystery around language. And I think if we really want to fill in the big jigsaw puzzle as it was about our story language is one of the really important pieces.