Attention to elders' voice in non-human primates.

The observed respect and attention to elders' speech in traditional cultures appears to have a 'universal' component which questions its possible biological bases. Animals present differential attention to the vocalizations of other individuals according to their characteristics but little is known about the potential propensity to pay more attention to vocalizations of elders. On the basis of several hundreds of vocal exchanges recorded, here we show that aged female Campbell's monkeys (Cercopithecus campbelli), despite being significantly less 'loquacious' than their younger adult counterparts, elicit many more responses when calling. These findings show that attention to elders' vocal production appears in non-human primates, leading to new lines of questioning on human culture and language evolution.