People dance, shake their heads, snap their fingers, clap their hands, or tap their feet to the beat of the music. It is something spontaneous and universal. This ability is typical of our species and has only been observed in some animals … Vocal learning, such as domestic parrots, are famous for following the beat of a melody with their heads apparently without any prior training. Well, two adult macaques, named Gilberto and Tomas, can do it too, by hitting with their hands. They synchronize their movements when Barry White’s song “You’re the First, the Last, My Everything” is played, among others, after their coaches, researchers from the National Autonomous University of Mexico, taught them how to do it with a metronome for a year.
The authors of the study, published Thursday in the journal Science, believe the experiment could shed light on the evolutionary roots of rhythm, and suggest that this meaning could be more widespread in the animal world than we think, even in creatures that have no vocal learning.
Macaques are not vocal learners, as the acoustic properties of their voices do not change with social experience, even if they have been raised for years with a different group. In the experiments, Gilberto and Tomas, two 10- and 12-year-old rhesus males from a breeding farm, listened to one of the songs chosen by the researchers and received a reward when they followed the rhythm appropriately. In addition to Barry White’s wonderful song, they heard Billy Bragg’s “New England”; “Passe & Medio Den Iersten Gaillar” by Josquin Des Prez, and the catchy “Everyboy” by the Backstreet Boys.
The test began when the monkey placed one hand on the grab bar and a yellow box appeared on the screen. Then, the music played and the yellow square disappeared, a signal for the monkey to start tapping with its hand to the beat of the music. The songs had a tempo—the speed of a piece of music, in beats or beats per minute (BPM)—of 465 ms, 732 ms, and 882 ms, which corresponds to tempos of 129 BPM, 82 BPM, and 68 BPM, respectively.
“The results were very surprising because from the beginning the animals started moving to the rhythm of the different songs we played them,” Hugo Merchant, a co-author of the study, told the newspaper. In fact, both animals developed consistent tapping rhythms across songs, and when the composers changed the tempo of the music, the macaques’ tapping phases changed as well, showing that they were in sync with the musical structure rather than responding to experimental cues, such as a color change on a screen. This behavior was observed even when the monkeys were shown a song they had never heard before, and when they were no longer rewarded for tapping to the beat.
In other mammals
Researchers believe that when an animal is able to coordinate auditory perception (the ability to extract temporal patterns from sound), prediction (the ability to anticipate rhythm), motor action (moving the body in sync with sound), and reward, it can synchronize with musical rhythm, even if it does not have complex vocal abilities. “Non-human primates have all the machinery in their vocal motor system to perceive the beat of the music and move with this subjective representation of the beat in a flexible and predictive way,” Merchant says.
Therefore, the study questions the idea that synchronization with musical rhythm is limited to humans or limited to species with vocal learning. This, in their view, expands our understanding of how different species perceive and respond to musical rhythm, and suggests that sense of rhythm could be a more widespread ability than we thought. “Mammals in general may have some or all of the auditory motor processing elements to simply track the beat of music, and when there is rigorous training they replay the responses in sync with the beat,” the researcher says.
However, the article has some drawbacks, let’s start with its small size. In a commentary accompanying the article in Science, Asif Ghazanfar and Gavin Stingo, researchers at Princeton University, point out that the authors “were careful to point out that the observed abilities were not natural behaviors: they were conditioned by extrinsic rewards, not the intrinsic rewards that humans experience when following rhythms.” Conditioned behavior may not be equivalent to behavior that arises spontaneously.
Ghazanfar and Stingo wonder whether such studies can really reveal anything about the evolution of human behavior. “Outside of music, could a monkey trained to ride a bicycle help understand human evolution in relation to cycling? -They ask- Studying this process will not reveal the ape’s hidden ability to ride a bicycle, but will simply show how conditioning can lead to the adoption of a human ability acquired through cultural evolution.
In his opinion, “the trained ability of the monkey could help determine the anatomical characteristics that allow primates to ride a bicycle: hands that can grasp, eyes that are directed forward, the ratio of limbs to each other, and the brain that coordinates these stimuli to move while balancing on two wheels.” Likewise, the authors show that monkeys can have a rhythm when trained, while noting that apes do not have a rhythm under natural conditions. The implications of their findings for the evolution of music remain insufficiently theorized.