A new analysis of the communication abilities of Chimpanzees might force a rethink on how unique our powers of speech really are.
A new study analyzed almost 5,000 recordings of wild adult Chimpanzees in a national park.
When they looked at the structure of the calls captured on the recordings, they were surprised to find that there were many different types of calls.
Compared to the endless possibilities of human sentence construction, there are 395 distinct sequences.
We have never quantified the communication capabilities of non-human primate because they have so many different things to say to each other.
The findings highlight a vocal communication system in Chimpanzees that is more complex and structured than previously thought.
Chimpanzees are known to combine single-use calls into a sequence, order calls within the sequence, and recombine independent calls into even longer sequences.
Chimpanzees have been studied before, but the sequence that makes up their entire vocal range had never been analyzed.
In order to correct this, the team captured 900 hours of vocal recordings made by 46 wild mature western chimpanzees.
In analyzing the vocalizations, the researchers found out how vocal calls could be combined in two-unit sequence or three-unit sequence. They mapped networks of how these utterances were combined, as well as examining how different kinds of frequent vocalizations were ordered and recombined.
grunts, pants, hoos, barks, screams, and whimpers are just a few of the different call types that were identified.
The researchers explain in their paper that single grunts are mostly emitted at food, whereas panted grunts are mostly emitted as a submissive greeting vocalization.
There are single hoos that are emitted to threats, but panted hoos that are used in inter-party communication.
The researchers found that they could combine different kinds of calls into a single sequence, which they say may be an underestimation, as new vocalization sequences were still being found.
The data so far suggest that Chimpanzees communication is more complex than we thought, which has implications for the sophistication of meanings generated in their utterances, as well as giving new clues into the origins of human language.
The researchers write that the vocal Chimpanzee system, consisting of 12 call types, can be used to create hundreds of different meanings.
This possibility is less than the infinite number of different meanings that can be generated by human language, but it still offers a structure that goes beyond that traditionally considered likely in primate systems.
The next step will be to record even larger datasets of Chimpanzees calls, to try to assess just how the diversity and ordering of uttered sequence relates to versatile meaning generation, which wasn't considered in this study.
Chimpanzees and scientists alike have a lot more to say.
Catherine Crockford is a director of research at the Institute for Cognitive Science in France.
By studying the rich complexity of the vocal sequence of wild Chimpanzees, we expect to bring fresh insight into understanding where we come from and how our unique language evolved.
The findings are reported in a journal.
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