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Are we able to differentiate between the vocal emissions of certain primates? A team from the University of Geneva (UNIGE) asked volunteers to categorise the vocalisations of three species of great apes (Hominidae) and humans. During each exposure to these ‘‘onomatopoeia’’, brain activity was measured. Unlike previous studies, the scientists reveal that phylogenetic proximity - or kinship - is not the only factor influencing our ability to identify these sounds. Acoustic proximity - the type of frequencies emitted - is also a determining factor. These results show how the human brain has evolved to process the vocal emissions of some of our closest cousins more efficiently. Find out more in the journal Cerebral Cortex Communications.
This is not only not what the research says, the premise is completely ridiculous.
From my scan of the article (not the paper), I surmise that they discovered that human ability to process primate vocalizations reflects not so much genetic relatedness as similarity in tones and ranges.
So how do those evolve? There needs to be co-evolution between speaking and listening parts of the brains. The study points out that bonobos, who like chimps are our closest living relatives, do not trigger the same human brain response as chimps.
We can come up with a number of hypotheses about why bonobos diverged faster (if that’s indeed what happened). It could be the different social structures or different geographic ranges, or some pressure back in evolutionary time that is no longer there but left its footprints in vocalizations.
The best research always raises more questions, and I think this is going to lead to some very interesting lines of investigation.
Yeah, you’re totally right. They definitely say that acoustic range distance can matter more than genetic distance. We are much more genetically related to bonobos than to macaques and yet people seem to be able to categorize macaque sounds better.
As to why it diverged for some species, that is very interesting. It certainly seems like geographic overlap could have something to do with it. If our ancestors were cohabitating more with chimps or macaques than bonobos, then maybe we would acoustically drift towards each other.
It would be interesting to do this sort of study with a wide range of animals. I imagine people would do really good with cats and dogs, but lots of animals we probably wouldn’t do better than chance. There may be some surprising ones though.