Isochronous singing in 3 crested gibbon species(Nomascus spp.)

The search for common characteristics between the musical abilities of humans and other animal species is still taking its frst steps.One of the most promising aspects from a comparative point of view is the analysis of rhythmic components,which are crucial features of human communicative performance but also well-identifable patterns in the vocal displays of other species.Therefore,the study of rhythm is becoming essential to understand the mechanisms of singing behavior and the evolution of human communication.Recent fndings provided evidence that particular rhythmic structures occur in human music and some singing animal species,such as birds and rock hyraxes,but only 2 species of nonhuman primates have been investigated so far(Indri indri and Hylobates lar).Therefore,our study aims to consistently broaden the list of species studied regarding the presence of rhythmic categories.We investigated the temporal organization in the singing of 3 species of crested gibbons(Nomascus gabriellae,Nomascus leucogenys,and Nomascus siki)and found that the most prominent rhythmic category was isochrony.Moreover,we found slight variation in songs’tempo among species,with N.gabriellae and N.siki singing with a temporal pattern involving a gradually increasing tempo(a musical accelerando),and N.leucogenys with a more regular pattern.Here,we show how the prominence of a peak at the isochrony establishes itself as a shared characteristic in the small apes considered so far.

Erratum to: Born to sing! Song development in a singing primate

The pagination of this article online has been updated to pages 597-608 to match the print version.The Publisher sincerely apologizes for introducing this error online.

Born to sing!Song development in a singing primate

In animal vocal communication,the development of adult-like vocalization is fundamental to interact appropriately with conspecifics.However,the factors that guide ontogenetic changes in the acoustic features remain poorly understood.In contrast with a historical view of nonhuman primate vocal production as substantially innate,recent research suggests that inheritance and physiological modification can only explain some of the developmental changes in call structure during growth.A particular case of acoustic communication is the indris’singing behavior,a peculiar case among Strepsirrhine primates.Thanks to a decade of intense data collection,this work provides the first long-term quantitative analysis on song development in a singing primate.To understand the ontogeny of such a complex vocal output,we investigated juvenile and sub-adult indris’vocal behavior,and we found that young individuals started participating in the chorus years earlier than previously reported.Our results indicated that spectro-temporal song parameters underwent essential changes during growth.In particular,the age and sex of the emitter influenced the indris’vocal activity.We found that frequency parameters showed consistent changes across the sexes,but the temporal features showed different developmental trajectories for males and females.Given the low level of morphological sexual dimorphism and the marked differences in vocal behavior,we hypothesize that factors like social influences and auditory feedback may affect songs’features,resulting in high vocal flexibility in juvenile indris.This trait may be pivotal in a species that engages in choruses with rapid vocal turn-taking.