University of Vienna
A cognitive biologist foresees breakthroughs in understanding vocal learning.
Vocal learning — the capacity to reproduce sounds heard in the environment — is key to human speech. Humans are alone among primates in having vocal-learning abilities, but a surprising variety of non-primates, such as songbirds and parrots, are also excellent vocal learners. The list of mammals with the ability is comparatively short, comprising humans, some whales and seals, and probably elephants. Now research on tropical bats has added another creature to the list.
Mirjam Knörnschild at the University of Erlangen-Nuremberg in Germany and her colleagues studied sac-winged bats (Saccopteryx bilineata) in Costa Rica (M. Knörnschild et al. Biol. Lett. 6, 156–159; 2010). Male Saccopteryx produce elaborate courtship displays that include complex songs. Surprisingly, young bats also produce songs, and acoustic analysis showed that as the bats grew older, their songs became more like those of the local territorial male. For about half the pups, the local male was not their father, ruling out simple genetic effects. Moreover, pups’ songs often became less species-typical over time, ruling out simple maturation. This research thus provides the first clear evidence for complex vocal learning in bats.
The finding is exciting for several reasons. First, the species is the only mammalian vocal learner that could conveniently be kept and eventually bred in the lab, opening the door to detailed scientific investigation. Second, previous work suggests that the FOXP2 gene, which is known to be involved in vocal learning in humans and birds, has also been under strong selection in bats, although we don’t yet know why. Echolocation is probably part of the answer, but this study suggests that social communication could be another. I believe that research on Saccopteryx will usher in an era of increased understanding of mammalian vocal learning.