Dr Katie Slocombe, York University
Pomme; ap-vel apple; mela– human language is gloriously diverse but is this the same for other species, like chimpanzees? Is there a universal chimpanzee language with dialects and accents? Or would a Scottish chimp and Dutch chimp just cross wires? A paper published in Current Biology has been answering just this question. Graihagh Jackson reports…
...chimp called Frek saying apples.
But does that sound mean ‘apples' everywhere in the chimp kingdom? If a Dutch chimp went to Scotland and met a Scottish chimp – no, this isn’t some terrible joke – and wanted to talk about apples or apfels in Dutch, would they understand each other? Would they adapt to become more Scottish in their accent, learn English for apples or simply shout apfel louder and louder, and slower and slower, like us humans do? Well, this is exactly what Katie Slocombe from the University of York has been trying to find out. Nine Dutch chimps were put into an enclosure with 9 Scottish chimps Edinburgh Zoo.
Graihagh - Chimps make certain calls for certain foods, just like humans have words for things. This is a Dutch chimp called Frek saying apples. (sound) But does (sound) mean ‘apples' everywhere in the chimp kingdom? If a Dutch chimp went to Scotland and met a Scottish chimp – no, this isn’t some terrible joke – and wanted to talk about apples or apfels in Dutch, would they understand each other? Would they adapt to become more Scottish in their accent, learn English for apples or simply shout apfel louder and louder, and slower and slower, like us humans do? Well, this is exactly what Katie Slocombe from the University of York has been trying to find out. Nine Dutch chimps were put into an enclosure with 9 Scottish chimps Edinburgh Zoo.
Katie - Yes, so we were actually just very fortunate to be in the right place at the right time. this was a big challenge for Edinburgh Zoo. So, they brought these new Dutch chimps over to really enlarge the Edinburgh group and have an active breeding group. And so, we were able to just get in and before they integrated them into this big group – record their calls and their preferences and then track them over time as they live together and started to get to know each other.
Graihagh - To begin with, they had very different calls and very different food preferences. The Dutch chimp Frek and his companions really liked apples and had quite high pitched calls as you heard before. The Scottish chimps however were not so keen on the old apples. Meet Lucy, the Scottish chimp. It’s quite hard to hear, but essentially, it’s a low grunt and nothing like the high-pitched shrieks that Frek makes when he see apples.
Katie - We focused on the apple calls because that's where we found a really interesting difference between the two groups. So, the Edinburgh chimps, they didn’t particularly like the apples and they gave these low pitched, quite gruff sounding grunts...'UH UH UH'- like that. and in contrast, the Dutch chimps who really like the apples gave much higher pitch, more tonal grunts, more ...'ah ah ah!'. And so, at the beginning in 2010, we had a really clear difference in the calls that these two groups of chimps were actually giving for the same type of food.
Graihagh - And so, you put the Dutch chimps in with these Scottish chimps to see how their calls and tones were changed.
Katie - Yes. So, just 1 year after integration, so after a whole year of living together, disappointingly, we found nothing had changed. But we then looked at the social data and actually found that although they were living together in one enclosure, they didn’t really like each other very much. So, they weren’t spending much time with members of the opposite group. So, when we came back in 2013 – so, they'd had 3 years now to live together and get to know each other – the social data then showed that they actually started to like each other. So, they'd form some really strong friendships kind of across those original groups. It was at that point that then we found that their calls have actually converged. We found that the Dutch chimps had changed their calls to sound much more like the Edinburgh chimp’s calls.
Graihagh - This is the old Frek...(sound). Now meet the new Frek...(sound). And compare it with Lucy, the Scottish chimp again...(sound). It’s practically the same. Frek and his Dutch friends became more like the Scots, but why not the other way around? Katie theorises that this is perhaps because the Scottish chimps were more dominant or perhaps there was more pressure on the Dutch chimps to fit in because they were immigrants. But the Dutch didn’t completely pander to the Scots.
Katie - Although the Dutch chimps were now giving a much lower pitched call, they actually still really loved apples.
Graihagh - And I suppose this is all quite surprising because my understanding is that they thought the key difference between chimps and human language is that chimps couldn’t adapt their calls like humans can – i.e. I might sound more northern when I'm talking to a northern person. So, to find out that chimps can is quite surprising.
Katie - Yes, indeed. It’s really exciting. Previously, we thought that all other primate calls, the structure of those calls is really determined by their arousal or their emotional state. And they don't really have much control over the structure of their calls. Humans seem to be really special in that way. But what this study shows is that actually, although they're not coming up with new calls to label things in their environment, but they are able to change the acoustic structure. Because we found that change happened independent of their preference for apples, it does seem to be that the first evidence that they can control the structure of their calls independent from the emotion or the arousal that they're actually feeling, so that's really exciting.