Primates communicate not only because they are biologically hardwired to do so, but also because they pursue specific goals during social interactions. This is well documented in the context of ape gestural signals, which have revealed a considerable degree of flexibility in interesting ways. In terms of vocal behavior, however, both monkeys and apes appear to be much less flexible, which raises important questions about how and why vocal flexibility evolved in the human lineage. The emerging picture is that, across the primate order, flexibility is widespread in call comprehension but largely restricted to humans in call production. Non-human primates, including the great apes, are curiously constrained by weak motor control over their vocal apparatus, resulting in limited vocal repertoires. A key transition in the evolutionary origins of language may have been when early humans began to interact with each other collaboratively. Another prediction is that, the species in which infants are exposed to competition over non-maternal caregivers should be more likely to exhibit elaborate vocal behavior than species in which their mothers raise infants only. Research on the communicative skills of other cooperative breeders, particularly communal breeders, may provide interesting empirical data to test this hypothesis.
Keywords: non-human primates; vocal repertoires; communicative skills; modern humans; vocal control
Article. 4128 words.
Subjects: Linguistics ; Language Evolution
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