Listening to grey seals recite vowel sounds and sing the melodies to Star Wars and 'Twinkle, Twinkle, Little Star' makes for excellent entertainment, but for the researchers who trained these aquatic mammals, it’s serious science.
Animals make all sorts of wacky sounds, and some are even good at imitating the sounds of other animals. The mockingbird, for example, famously mimics the sounds produced by other bird species, and sometimes even noises produced by human activity, like car alarms and police sirens. Some parrots and ravens are really good at imitating human speech but, for the most part, this is an ability that eludes most animals. That’s a shame, because it prevents scientists from studying vocal learning, a trait critical for language acquisition in nonhuman mammals.
As new research published this week in Current Biology shows, grey seals appear to be an exception. In a series of tests, these mammals demonstrated a remarkable capacity to copy simple melodies and human formants, suggesting they’re very capable vocal learners.
“Formants” in this case refers to variable frequency bands produced by the vocal tract that enable us to make vowel sounds. Seals, as it turns out, are really good at producing formants, and they’re also pretty clever, making them ideal test subjects for the new study, led by Amanda Stansbury and Vincent Janik from the Scottish Oceans Institute (SOI) at the University of St. Andrews in Scotland.
“The anatomical structures used for producing vocalisations such as the vocal cords, larynx and mouth cavities are the same for seals and humans,” Janik told Gizmodo. “Other vocal learners use different structures. Birds, for example, do not have a larynx but a different structure called a syrinx to produce sounds. Dolphins use muscles in their nasal air passages to produce learned sounds.”
The new study shows that grey seals can mimic some human speech sounds, and generate noises outside their normal vocal range, while doing so in a manner similar to humans.
A grey seal. Image: University of St. Andrews
Three young grey seals were used in the study: Gandalf, a male, and Zola and Janice, two females. The seals were born on the Isle of May and brought to the marine mammal facility at the University of St. Andrews when they were very young, with training starting shortly thereafter and lasting for 12 months. The three seals were allowed to co-mingle with other juveniles in three enclosures, and they were released back into the wild a year after they were captured.
“We first taught them to produce their own seal sounds in response to our training signals,” said Janik. “We then changed those sounds in the computer to create different pitches and melodies. Once they succeeded in copying these tunes, we presented vowels spoken by a human and transferred to an easier frequency band for the animals.”
Zola demonstrated a proficiency at copying melodies, singing up to 10 notes of songs like 'Twinkle, Twinkle Little Star' and the melody to Star Wars. Janice and Gandolf were able to replicate combinations of human vowel sounds. Over the course of hundreds of trials, the seals were able to copy and express all possible vowel combinations of A, E, I, O and U.
“The vocal learning abilities of seals had not been explored before,” said Janik. “One of the next questions is how they use this skill in their own communication. It hints at a more complex communication system than what was assumed for seals before.”
Janik said these findings could be used in marine conservation and in comparative studies on vocal development.
“First, knowing how seals use sounds is important to assess how they are affected by noise created by human activities such as shipping or marine construction,” he explained. “This, in turn, will help us to manage wild populations more carefully. Second, studying how vocal learning works in seals and how it might be naturally impaired in some individuals can help to understand vocal development and its limitations in other mammalian learners that use similar structures, such as humans.”
In addition, these findings could also offer important evolutionary insights into the emergence of speech and language.
Seals singing Star Wars is obviously pretty cool, but the researchers missed a rather obvious opportunity to have a seal sing Seal. Perhaps next time.