Convergence of calls as animals form social bonds, active compensation for noisy communication channels, and the evolution of vocal learning in mammals

Abstract

The classic evidence for vocal production learning involves imitation of novel, often anthropogenic sounds. Among mammals, this has been reported for African elephants, harbor seals, and dolphins. A broader taxonomic distribution has been reported for vocal convergence, where the acoustic properties of calls from different individuals converge when they are housed together in captivity or form social bonds in the wild. This kind of vocal convergence has been demonstrated for animals as diverse as songbirds, parakeets, bats, elephants, cetaceans, and primates. For most of these species, call convergence is thought to reflect a group-distinctive identifier, with shared calls reflecting and strengthening social bonds. Pooling data on vocal imitation and vocal convergence suggests a wider taxonomic distribution of vocal production learning among mammals than generally appreciated. The wide taxonomic distribution of this evidence for vocal production learning suggests that perhaps more of the neural underpinnings for vocal production learning are in place in mammals than is usually imagined. One ubiquitous function for vocal production learning that is starting to receive attention involves modifying signals to improve communication in a noisy channel.