Vocal learning in bottlenose dolphins (Tursiops truncatus) : affect, control, and discrimination

Abstract

The origin of human language remains one of the biggest unanswered questions in our evolutionary history. One of the fundamental traits of language acquisition is vocal learning. Vocal learning is a rare trait, only present in four mammalian clades outside of humans. This thesis furthers our understanding of the origin of language through a comparative assessment of a vocal learning mammal, the bottlenose dolphin (Tursiops truncatus). Such comparative analyses shed light on what convergent features we share that lead to the evolution of vocal learning and what features have diverged that have contributed to the evolution of language.

Chapters 2 and 3 investigate the ability of a species to produce vocalisations through choice rather than a reflexive or emotionally driven behaviour. I propose a new framework that allows us to measure such vocalisations in an experimental setting, alleviating the pitfalls of previous analysis. I then test whether this framework can be applied in an experimental paradigm using bottlenose dolphins as a subject species. One overlooked component of vocal learning is perception, since it dictates how an individual will model vocal output. Chapter 4 presents the first evidence of the Clever Hans Effect in a bottlenose dolphin, where unconscious cues can lead subjects to the correct answer that has wide implications for the field of animal behaviour. Chapter 5 reviews the ability of a bottlenose dolphin to discriminate between the vocalisations of conspecifics and heterospecifics. Chapter 6 ties together both perception and production as it reveals how dolphins modify the production of both whistles and burst pulses in positive, neutral, and negative affect contexts and their ability to convey internal emotional state to each other.