As human children learn to talk, they begin to pick up on the rule that interrupting is not allowed—although it may take some parental nagging for the rule to sink in. Monkeys are no different, new research shows. The core of communication in Campbell's monkeys (Cercopithecus campbelli), which are native to western Africa, revolves around alternating vocal calls. Researchers recorded spontaneous utterances of both young and adult monkeys and tallied how often each broke the rules of alternating calls. The adults broke the rules--calling twice in a row instead of letting another monkey take its turn—less than 1% of the time. The juveniles, however, were rule-breakers in 13% of their calls. Moreover, when played calls that either followed conversational rules or didn't, adults gave more attention to conversations with a clear alternating pattern, whereas juveniles didn't seem to differentiate. The findings, which appear today in Scientific Reports, could help scientists learn more about how language evolved in humans—just as long no one cuts anyone else off.
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