Chimpanzees have been shown to have a complex kind of gestural communication, and in unprecedented detail scientists have now just finished compiling a kind of dictionary to help us better understand these interactions.
Publishing this month in the science journal Current Biology, researchers from the University of St. Andrews, Scotland, set out to build on previous research that has shown chimps use complex gestures to communicate. To investigate whether chimps really are using particular gestures consistently, the researchers studied more than 4,500 gestures from 3,400 chimpanzee interactions that were captured on film in Uganda between 2007 and 2009.
In total, the researchers were able to document 66 unique hand gestures and boil those down to 36 gestures (so stripping away similar gestures), and identified 15 specific meanings. These consistent hand gestures could be used either on their own or in conjunction with other gestures. This appears to offer the chimpanzees a hereto little understood degree of complexity in their communication.
The researchers found that, crucially, the gestures remained largely consistent no matter which chimpanzees were using them. They were also observed using these skills in settings with many other chimps, providing us an insight into the social life of chimps in a way we haven’t necessarily been able to observe before. This all begs the question, though, what are the chimps actually saying to each other?
A mother chimpanzee displaying the sole of her foot to her child appears to mean she wants her baby to climb onto her. If the chimpanzees had an itch, they would touch the arm of another to say “scratch me.” Open arms, as if hugging the air, was observed to probably mean “I want contact.” Meanwhile, feet stomping seemed to suggest that the chimp wanted to play. The researchers also found that seemingly innocuous leaf chewing had little to do with nutrition and more to do with wanting sexual attention.
Interestingly, and as we’d expect from complex communication, some gestures and sequences appeared to convey more than one meaning. If one chimp grasped another chimp it could communicate several different things. It might mean the chimp was trying to say “stop,” sometimes it meant “climb on me,” and other times it meant the chimp wanted to be left alone.
The researchers believe that this analysis should just be the start of their lexicon development because it’s likely that these first observations have missed some of the nuance in these communications. For instance, while it appeared that several gestures might mean the same thing and so were discounted, it could be that they communicated slightly different meanings or betrayed slightly different intents.
“What we’ve shown is a very rich system of many different meanings,” said Richard Byrne of Scotland’s University of St. Andrews and co-author of the chimpanzee study. “We have the closest thing to human language that you can see in nature.”
So how close to human language is this? Well, the gestures aren’t as varied or flexible as what humans produce through our verbal communication, and there doesn’t seem to be a concept of sentence structures or syntax. It’s important that we distinguish between language and communication though. While this does show that chimpanzees have language-like skills, we can’t yet say this amounts to a language because language is much more than just gestural communication.
Nevertheless, this is very exciting and not just for the insights it offers into chimpanzee life. It suggests to us that humans didn’t develop language as a fact of our being human, but that there is a cognitive basis for language that is in our makeup and it’s one that we share with other great apes and, it seems, our primate cousins. As a side-note, it also adds yet more weight to the calls for an end to chimpanzee research and confinement, which is an ongoing yet very necessary struggle.
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