Key issues in the study of primate acoustic signals, an update

In our earlier review (Gamba & Giacoma, 2005), we highlighted the fact that studies of non-human primate vocal communication would benefit greatly from an in-depth study of phona- tion processes, and that anatomical evidence from investigations of the vocal apparatus should be con- sidered. This is crucial from the perspective of the evolution of language and would allow an under- standing of whether other species can voluntarily produce “new” calls using different combinations of vocal tract configurations, temporal and funda- mental frequency patterns, or if they are unable to do so, due to genetic constraints on their commu- nicative abilities. From a behavioural perspective, these communicative abilities can also help in the interpretation of acoustic variability, for instance when similar vocalisations are used in different contexts. In the past few years, studies on primate vocal communication have made several advances, increasing our knowledge of the role played by acoustic variation in providing information about group composition, sex, age and individuality.