Vocal Creativity in Elephant Sound Production.

Abstract

Simple SummaryElephants are known for their complex vocalization system and for being able to imitate sounds. Here, we show that African elephants apply unusual and individualistic sound production mechanisms to generate idiosyncratic sounds. These sounds are produced by manipulating non-phonatory structures, e.g., applying an ingressive airflow at the trunk tip to emit extraordinarily high-frequency sounds or repeatedly contract superficial muscles at the trunk base to generate lower-frequency pulsated sounds. Intriguingly, each individual establishes its own distinctive sound-producing strategy (e.g., contracting different muscle bundles). The production of these sounds on cue is encouraged via positive reinforcement training. This suggests that social feedback and reinforcement can facilitate vocal creativity and learning behavior in elephants. Social interactions and positive feedback are also crucial for early speech learning in human infants. Increasing knowledge on sound production plasticity in elephants—long-living, highly social mammals—is crucial in the effort to better understand their communicative and vocal learning ability and its function in wild elephant populations.How do elephants achieve their enormous vocal flexibility when communicating, imitating or creating idiosyncratic sounds? The mechanisms that underpin this trait combine motoric abilities with vocal learning processes. We demonstrate the unusual production techniques used by five African savanna elephants to create idiosyncratic sounds, which they learn to produce on cue by positive reinforcement training. The elephants generate these sounds by applying nasal tissue vibration via an ingressive airflow at the trunk tip, or by contracting defined superficial muscles at the trunk base. While the production mechanisms of the individuals performing the same sound categories are similar, they do vary in fine-tuning, revealing that each individual has its own specific sound-producing strategy. This plasticity reflects the creative and cognitive abilities associated with ‘vocal’ learning processes. The fact that these sounds were reinforced and cue-stimulated suggests that social feedback and positive reinforcement can facilitate vocal creativity and vocal learning behavior in elephants. Revealing the mechanism and the capacity for vocal learning and sound creativity is fundamental to understanding the eloquence within the elephants’ communication system. This also helps to understand the evolution of human language and of open-ended vocal systems, which build upon similar cognitive processes.