Bilingual chimpanzees?

Maybe you came across these news last week: a group of chimpanzees from a Dutch zoo was moved to a zoo in Scotland where the newcomers adopted the local grunts for apples. That is actually quite a nice story Watson and colleagues, from the University of York, report in Current Biology. They recorded the sounds of either individual of the two groups when they encountered apples. What the analysis shows is that the initially high-pitched calls from the Dutch chimpanzees converged towards the softer calls from the Scottish conspecifics.

So far, it was assumed that the sounds primates produce are based on their emotional state, e.g. arousal when confronted with their favourite food (in this case apples – not bananas). Therefore, it was assumed that these sounds are fixed referential calls that would not change. Although prior studies have shown that these calls can be modified, the present study appears to be the first that demonstrates that non-human animals actively adapt referential vocalisation due to social learning from conspecifics.

Interestingly, this transition took three years (data was recorded from 2010 to 2013). The authors explain this with the time it took for the social integration of the two groups.

So, what is so special about this finding? Well, while different popular science sources like BBC, ScienceDaily, and NewScientist immediately proclaimed bilingual chimpanzees and the end of the uniqueness of human language, the authors of the study are a bit more careful in phrasing their insights. The finding that the ‘grunts’ are not as rigid and fixed as initially thought brings them closer to referential words used by humans. And because referential words are the fundament of human language its principle concept might go far further back in time than previously thought.

But is it true that the Dutch chimpanzees learned Scottish? No, says Brandon Wheeler of the University of Kent in the NewScientist article. What the researchers observed is less a form of learning a language but rather adopting a different accent for the same emotional sound.

In any case, it is an interesting study that calls for follow up studies. For example, can we observe that ‘foreign’ chimpanzees learn a referential grunt for something they have not experienced before? To me it is also interesting why the Dutch group learned the Scottish grunt, although they were the slightly bigger group. Pure chance? Did the Dutch chimpanzees preferred the softer grunt over their own’s? Future studies might show.

Sources | CurrentBiologyScience | NewScientist | ScienceDaily | BBC 

Watson, S. K., Townsend, S. W., Schel, A. M., Wilke, C., Wallace, E. K., Cheng, L., … Slocombe, K. E. (2015). Vocal Learning in the Functionally Referential Food Grunts of Chimpanzees. Current Biology, 25(4), 495–499. doi:10.1016/j.cub.2014.12.032