Rhythm is important to human music and speech. But are we the only mammal with a sense of rhythm? In an experimental study published in Biology Letters, a team of researchers led by the Max Planck Institute for Psycholinguistics in Nijmegen and the Sealcentre Pieterburen show that seals can discriminate rhythm without prior training. The rhythmic ability of seals may be linked to their ability to learn vocalizations, skills that may have co-evolved in humans and seals.
Why are we talkative and musical animals? Evolutionary biologists believe that our speech and musical abilities may be linked: only animals capable of learning new vocalizations, such as humans and songbirds, seem to have a sense of rhythm. “We know that our closest relatives, the non-human primates, need to be trained to respond to rhythm,” says first author Laura Verga. “And even when trained, primates show rhythmic abilities very different from ours.” But what about other mammals?
seal rhythm
The researchers decided to test the rhythmic abilities of harbor seals, animals known to be capable of vocal learning. The team first created sequences of seal vocalizations. The sequences differed in three rhythmic properties: tempo (fast or slow, like beats per minute in music), length (short or long, like the duration of musical notes), and regularity (steady or irregular, like a metronome compared to the rhythm of free music). Jazz). Would baby seals react to these rhythmic patterns?
The team tested twenty young seals held in a rehabilitation center (the Dutch Sealcentre Pieterburen) before being released into the wild. Using a method taken from studies on human infants, the team recorded the number of times the seals turned their heads to look at the sound source (behind their backs). Such staring behavior indicates whether animals (or infants) find a stimulus interesting. If seals can distinguish between different rhythmic properties, they may look longer or more often when they hear a sequence they prefer.
Seals looked more often when vocalizations were longer, faster, or rhythmically regular. This means that yearling seals – without training or rewards – spontaneously distinguished between regular (metronomic) and irregular (arrhythmic) sequences, sequences with short or long notes, and sequences with a fast or slow rhythm. .
Evolutionary origins
“Another mammal besides us shows rhythm processing and vocalization learning,” Verga says. “This is a significant advance in the debate about the evolutionary origins of human speech and musicality, which are still quite mysterious. As with human babies, the perception of rhythm we find in seals emerges early in life, is hardy and requires no training or reinforcement.”
Next, Verga and his team want to know if seals perceive the rhythm of other animals’ vocalizations, or even abstract sounds; and if other mammals show the same skills: “Are seals special, or are other mammals also able to spontaneously perceive rhythm?”
Anatomical study confirms that harbor seals are good at learning various calls
Laura Verga et al, Spontaneous rhythmic discrimination in a mammalian vocal learner, Biology Letters (2022). DOI: 10.1098/rsbl.2022.0316. royalsocietypublishing.org/doi….1098/rsbl.2022.0316
Provided by the Max Planck Society
Quote: Seals have a sense of rhythm (2022, October 25) retrieved October 25, 2022 from https://phys.org/news/2022-10-rhythm.html
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