Speech‐like orofacial oscillations in stump‐tailed macaque (Macaca arctoides) facial and vocal signals

Abstract

These results indicated a common mechanism for the central pattern generator underlying orofacial movements, which would evolve to speech. Similar oscillations in panting, which evolved from different muscular control than the orofacial action, suggested the sensory foundations for perceptual saliency particular to 5-Hz rhythms in macaques. This supports the pre-adaptation hypothesis of speech evolution, which states a central pattern generator for 5-Hz facial oscillation and perceptual background tuned to 5-Hz actions existed in common ancestors of macaques and humans, before the emergence of speech.

Sequence and hierarchy in vocal rhythms and phonology

“…What is more, monkeys show a preference for computer‐animated lip smacks at this speech rate, additional evidence for perceptual “tuning” to these displays. Similar rates of vocal modulation have been recently shown in multiple primate vocalizations …”

“…If Darwin was correct, what structural properties might these early songs have had? Clearly, proto‐musical songs would have had “rhythm” in the sense that modern speech does, at a rate roughly shared by many nonhuman primate vocalizations . Whether these earliest songs also had an isochronic beat cannot be determined.…”

“…Similar rates of vocal modulation have been recently shown in multiple primate vocalizations. 109,110,114,115 An important recent paper used functional magnetic resonance imaging to examine brain activation in macaques who were induced to produce lip smacks by showing them videos of conspecific faces. 116 The production of these communicative facial gestures activated both medial and lateral motor areas, though with a bias toward the medial regions.…”

Rhythm in speech and animal vocalizations: a cross‐species perspective

“…Focusing on individual vocal rhythms, early descriptive work remarked temporal regularities in gelada monkeys’ vocalizations, a claim which is intriguing but purely descriptive, unfortunately not supported by quantitative data or statistical inference. More recent work in macaques and orangutans noted a 5‐Hz isochronous pattern during lip‐smacking, facial movement, or vocalization . Primate perspectives on speech rhythm can be found elsewhere (e.g., see Ref.…”

“…More recent work in macaques and orangutans noted a 5-Hz isochronous pattern during lip-smacking, facial movement, or vocalization. [35][36][37] Primate perspectives on speech rhythm can be found elsewhere (e.g., see Ref. 21), but it is clear that we do need to understand more about vocal rhythms in our closest living relatives, the primates.…”