Synchronised swimmers: Seals have a sense of rhythm, scientists learn

Researchers say their findings are a ‘significant advance’ in the understanding of the mysterious origins of human speech and musicality, reports Maryam Zakir-Hussain

Seals have a sense of rhythm, scientists learn (Getty Images/iStockphoto)

Evolutionary biologists have found that seals are able to pick up rhythms in a way that is similar to human’s capacity for speech and music from a young age.

Existing research has shown only animals that can learn new vocalisations—such as humans and songbirds—seem to have a sense of rhythm.

“We know that our closest relatives, non-human primates, need to be trained to respond to rhythm”, said Laura Verga, a postdoctoral researcher at the Max Planck Institute for Psycholinguistics. “And even when trained, primates show very different rhythmic capacities to ours”.

In a study published in Biology Letters, researchers led by Ms Verga tested the rhythmic abilities of harbour seals, animals known to be capable of vocal learning.

The team first created sequences of seal vocalisations. The sequences differed in three rhythmic properties: tempo (fast or slow, like beats per minute in music), length (short or long, like duration of musical notes) and regularity (regular or irregular, like a metronome vs the rhythm of free jazz).

The team tested 20 young seals being cared for at Dutch Sealcentre Pieterburen rehabilitation centre before they were released into the wild.

Using a method from human infant studies, the team recorded how many times the seals turned their head to look at the sound source behind their backs.

Such looking behaviour indicates whether animals find a stimulus interesting. If seals can discriminate between different rhythmic properties, they might look longer or more often when they hear a sequence they prefer.

The seals looked more often when vocalisations were longer, faster, or rhythmically regular. This means that the one-year-old seals—without training or rewards—spontaneously discriminated between regular (metronomic) and irregular (arrhythmic) sequences, those with short versus long notes, and sequences with fast versus slow-paced tempo.

“Another mammal, apart from us, shows rhythm processing and vocalisation learning”, Ms Verga said. “This is a significant advance in the debate over the evolutionary origins of human speech and musicality, which are still rather mysterious.

“Similarly to human babies, the rhythm perception we find in seals arises early in life, is robust and requires neither training nor reinforcement.”

The team now want to find out whether seals perceive rhythm in vocalisations of other animals, or even abstract sounds, as well as whether other mammals show the same skills.

Ms Verga said: “Are seals special, or are other mammals also capable of spontaneously perceiving rhythm?”