Experimental evidence for the co-evolution of hominin tool-making teaching and language

Vocal learning in a social mammal: Demonstrated by isolation and playback experiments in bats

The evolution of human language is shrouded in mystery as it is unparalleled in the animal kingdom. Whereas vocal learning is crucial for the development of speech in humans, it seems rare among nonhuman animals. Songbirds often serve as a model for vocal learning, but the lack of a mammalian model hinders our quest for the origin of this capability. We report the influence of both isolation and playback experiments on the vocal development of a mammal, the Egyptian fruit bat. We continuously recorded pups from birth to adulthood and found that, when raised in a colony, pups acquired the adult repertoire, whereas when acoustically isolated, they exhibited underdeveloped vocalizations. Isolated pups that heard bat recordings exhibited a repertoire that replicated the playbacks they were exposed to. These findings demonstrate vocal learning in a social mammal, and suggest bats as a model for language acquisition.