When you cringe at shrieking violins in a horror movie or feel your spirit lifted by a buoyant pop song, you’re doing something scientists have rarely observed in the animal kingdom: having different emotional responses to different types of music. Now, pigs are providing compelling new evidence that animals may respond emotionally to music as well. The find may lead to ways to improve their welfare on farms.
“It’s a really neat study” that shows animals are more emotionally attuned to music than people think, says Charles Snowdon, a psychologist and animal behavior expert at the University of Wisconsin, Madison, who wasn’t involved with the work. “We’ve been trying to argue this for a decade, so it’s nice to see this empirical work support that.”
Music is sometimes used as enrichment for farm and other captive animals. And Snowball the dancing cockatoo likes to boogie to the Backstreet Boys. But whether these creatures have a true emotional response to the tunes is unclear.
That’s what the new study aimed to do—but with pigs. Co-author Maria Camila Ceballos, an animal welfare scientist at the University of Calgary, says she and her colleagues chose these animals because they are highly intelligent and social, and face serious welfare challenges on factory farms.
In the new study, Ceballos’s colleague Berardo de Jesús Rodríguez, a veterinarian and musician at the University of Antioquia, Medellín, composed 16 pieces of music featuring piano, strings, wind instruments, and percussion melodies that were either primarily consonant or dissonant. To humans, consonant music generally sounds pleasant and smooth—think a C major chord—whereas dissonance tends to sound jarring and uncomfortable, such as the score from Alfred Hitchcock’s Psycho.
The team then filmed six litters of 10 to 12 young pigs listening to the music through a speaker at a university pig farm. The musical pieces, each lasting about 3 to 5 minutes, were played in a random order with a 3-minute break in between.
The researchers scored the pigs’ body language on 20 emotional parameters, including “content” and “uneasy” using an approach called qualitative behavioral assessment (QBA). The method involves looking at an animal’s posture, demeanor, and interaction with its environment. For example, QBA can distinguish pigs that have been given the antitension drug azaperone from those who haven’t, because they consistently appear more visually curious and less nervous. Stressed animals with higher heart rates and body temperatures can also be visually identified as more agitated and restless through QBA.
Pieces of consonant music were linked to the pigs experiencing positive emotions, whereas the dissonant music was linked to negative emotions, the team reports this month in Scientific Reports. “So we found that, yes, music generates different emotions,” Ceballos says. (The pigs’ reactions to the different music can be seen in the video above.)
Animal welfare scientist Jun Bao from the Northeast Agricultural University in China is skeptical about whether Ceballos’s team detected emotions, however. He recently found that exposure to string and wind music increases play and tail wagging in pigs, which he sees as signs of a “positive mood.” However, he says it’s not clear that pigs labeled as “happy” or “uneasy” through QBA actually experience those emotions.
Snowdon says the emotional descriptions are a matter of interpretation. In his own work, he has seen monkeys shake their heads, jump swiftly between perches, and have their fur stand on end in response to music. “We didn’t use the word emotion,” he says, “but they showed behaviors that we think are indicative of anxiety.”
Ceballos hopes the study will help researchers create welfare-improving music, tailor-made to a specific species. Bao agrees that music can probably be therapeutic to stressed animals. Still, he is unsure about its usefulness with healthy animals who might eventually lose interest. “But it’s really interesting, because if it works, it would be the handiest and cheapest way to enrich their environment.”