Review of plasticity and flexibility in vocal communication in New World monkeys

Abstract

Vocal plasticity and flexibility in New World monkeys typically involve modification of existing vocal repertoire and voluntary control over certain aspects of vocal production. This ability is crucial for effective communication within their diverse social and environmental landscapes, enhancing chances of survival. Although recent research has shown vocal plasticity and flexibility within specific species, there has been no comprehensive review addressing New World monkeys collectively. This review examines the current literature concerning the plasticity and flexibility of vocal communication in New World monkeys. Our investigation revealed five indicators of vocal plasticity and flexibility in New World monkeys across various studies: the Lombard effect, individual vocal recognition, vocal learning, turn-taking and deception. While certain species exhibit one or two of these markers, there is a lack of research examining the extent to which New World monkeys exhibit these markers. Our paper also discusses the validity and mechanisms behind these five markers of vocal plasticity and flexibility. Our findings reveal not only the extent of vocal adaptability within these New World monkeys but also the need for further systematic research to address the gaps in our understanding of vocal plasticity and flexibility in New World monkeys, therefore providing direction to future researchers. Additionally, we propose that future research should see vocal plasticity and flexibility in New World monkeys as a continuum, rather than from a simplistic binary perspective. Lastly, our findings have implications on conservation efforts, especially for species facing substantial threats as a result of limited vocal plasticity and flexibility.