Animals like parrots and songbirds have long gotten credit for copying human sounds and mastering melodies. Now, seals want some of that clout.
Scientists from the University of St. Andrews in Scotland have taught seals how to sing. In a study published on Thursday in Current Biology, researchers studying vocal learning trained young gray seals to mimic human vocal sounds and carry a tune.
Vocal learning is pretty rare in animals. Many species have a limited set of sounds they can make—like meows or barks—and these often don’t change much throughout their lifetime. In this study, researchers showed that gray seals were able to make completely new sounds after training, unlike any they had made before. In fact, the researchers taught them to mimic human vowel sounds and replicate tunes such as the Star Wars theme and Twinkle Twinkle Little Star.
In the animal kingdom, sounds are used to encode all sorts of different information. In gray seals, they use moans to communicate between mother and pup or to howl together in a chorus. Even before this study, there was already anecdotal evidence that seals could learn to sing. A talking seal named Hoover gained widespread fame in the 1980s for mimicking human speech. However, scientists remained puzzled as to why or how seals could vocalize in this way.
One big hint is their anatomy, according to the study. Though their vocalizations are much less varied than ours, the vocal tracts of gray seals closely resembles that of humans. So, scientists saw these seals as the perfect subjects with which to study vocal learning in non-human mammals.
Three seals were trained as part of this study: Zola, Janice, and Gandalf. Researchers trained the seals using positive reinforcement, giving them food when they performed well. If they didn't feel like getting out of the water for training, the researchers let them be, according to the study.
The seals underwent hundreds of training sessions, first learning to copy sequences of sounds that matched the frequency of their own moaning calls. Once they mastered these, they were taught to copy formants, or frequency bands. In humans, formants create vowel sounds, encoding important information necessary for speech.
Zola was able to replicate tunes, or sequences of frequency changes. Janice and Gandolf were tested on human vowel sounds, and could reliably mimic these by the end of testing.
Scientists have been trying to teach animals to talk for ages. Non-human primates have had surprisingly little success learning new sounds, while parrots can mimic whole conversations. This research in seals suggests that non-human mammals have the potential to learn some of the fundamental sounds that make up human language, opening the door for further studies on language learning.