Emotional communication in monkeys: Music to their ears?

The question of whether music is uniquely human is controversial with equivocal results on whether nonhuman animals can appreciate music. We argue that, although human music is unique to our species, the emotional aspects of music have a long evolutionary history. We fi rst present a theory of the emotional origins of music and then show that music/emotional features can be seen in the vocalizations of cotton-top tamarins, a small monkey from the New World. When we composed music comprising our hypothesized emotional features in the frequency range and tempos of tamarin vocalizations, and played these compositions to the monkeys, we could induce calming and arousing emotional states in the monkeys, although human-based music with similar features had little or no effect on the monkeys. Our results suggest that other species incorporate similar emotional features into their calls as are used in music to infl uence emotions. The results also suggest that calls are not merely communicating the caller’s emotional state but may be used to induce emotional responses in listeners. Furthermore, attempts to play human-based music to other species as enrichment are likely to be misguided, with human-based music either being irritating or merely ineffective.