By Layal Liverpool
Lutz Wiegrebe/Ludwig-Maximilians-Universität
Bats can learn to mimic specific sounds, which puts them into an elite group of animals capable of this. Studying how bats can copy noises could help us learn more about humans’ unique capacity for speech and language.
The ability to imitate specific sounds – called vocal production learning – is rare in the animal kingdom. Humans are capable of it, as are some bird species, as well as seals, dolphins, whales and elephants.
“It’s relatively difficult,” says Ella Lattenkamp at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands. “You have to memorise the sound, produce it and then you have to hear again what you just produced and compare it with the template in your head,” she says.
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Lattenkamp and her colleagues trained six adult pale spear-nosed bats to imitate their own calls by bribing them with food if they repeated the sound. The bats were placed in mini recording studios equipped with loud speakers, microphones and remote-controlled feeding devices that delivered them rewards.
The researchers recorded the bats’ calls, then manipulated the recordings to lower the frequency of the sounds. The bats then were repeatedly exposed to different sounds and rewarded with mashed banana whenever they imitated a sound correctly.
Within 30 days, all six bats had learned to lower the frequency of their calls to imitate the recorded sounds.
Vocal production learning is important for speech and so studying it in other mammals, like bats, could provide clues as to how it developed in humans.
Most studies of vocal production learning have focused on songbirds, says Lattenkamp. A previous study has found that bat pups can imitate sounds made by their parents, but until now it wasn’t clear whether bats retain the ability to learn and mimic new sounds in adulthood.
Lattenkamp says the team’s next step will be to investigate whether the adult bats that learned to mimic low frequency calls are also able to learn more complex sounds or sound patterns. “They haven’t been trained to sing yet,” she says.
But bats probably won’t be able to learn how to imitate anything as complicated as human speech, says Lattenkamp, because they don’t have the right physiology to produce the required sounds.
Journal reference: Biology Letters, DOI: 10.1098/rsbl.2019.0928
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