Making and enjoying music seems like an eminently human activity. We sing, play instruments, dance, clap, move our heads and set the rhythm with our feet instinctively when we listen to a song we like. The scientific community has been debating this for several years, when Charles Darwin transplanted it, whether these skills belong exclusively to us or are introduced by other animals as well. Now, a team of researchers from the National Autonomous University of Mexico (UNAM) has demonstrated that monkeys can synchronize their beats to the beat of real songs, even choosing to do so automatically when it is not necessary to obtain a reward. Al-Halazgo, was published in July of this year in the magazine sciencescontradicts the influential vocal learning hypothesis, which supports that only species capable of learning complex vocalizations—such as humans and some birds—can perceive and synchronize with musical rhythm.
The experiment was performed on adult male monkeys that had previously been trained to strike a surface to the beat of a metronome. If you call Gilberto y Thomas. Next, the researchers conditioned them to beat following the self-paced rhythm of three different songs, at tempos of 129, 82, and 68 beats per minute. The songs were chosen because they had a very clear tempo and because human listeners could understand where the song was falling. It’s about YYou are my first, last and everything By Barry White, New England By Billy Bragg and Renaissance Dance Bass & Medio/Den Ersten Gaillard By Josquin de Perez. Y Gilberto y Thomas Follow the rhythm.
“This is an idea that has been around for 20 years,” explains Hugo Merchant, who directed the study and head of the Department of Developmental Neurobiology and Neurophysiology at UNAM (National Autonomous University of Mexico). To prove that the mono is indeed synchronized with the characteristics of the music, the researchers displayed the visual cue that indicates when the beat begins. If the animals were left to follow the visual signal alone, their stroke pattern would not change. But the results showed that the monkeys adjusted the phase of their beats depending on the characteristics of the music.
Perhaps most surprising was that when the monos were allowed to beat freely at any interval of their choosing—without requiring any set time—they continued to automatically sync with the beat of the music. Although they can receive a reward by producing any fixed interval, animals naturally tend to strike at the correct time. “We introduce new songs that none of them have heard before,” explains Vani Rajendran, first author of the analysis, also a researcher at UNAM. “Most of the time, the monkeys pick the beat that really fits the song. That tells me they’re trained, but they have that ability. Once they learn the rules, they apply them to any song.”
Halzgo questions the vocal learning hypothesis, proposed by neuroscientist Anirudh Patel. This theory suggests that the ability to synchronize with musical rhythms is linked to brain circuits that arise with vocal learning. However, monkeys are not vocal learners: the characteristics of their vocalizations do not change according to social experience. When they saw what the monkeys could do, the scientists became very emotional, and they recognized both researchers in a video conference with EL PAÍS.
“This research is pioneering in exploring the ability of non-human primates to synchronize with the pulse of a real musical piece,” confirms SMC España portal Ferran Mayayo, support technician in the investigation of this topic at the Pompeu Fabra University. Furthermore, he explains that the research has “remarkable scientific importance, as it advances knowledge of the rhythmic capabilities of non-human primates.”
Asif Ghazanfar, a neuroscientist at Princeton University, writes an analysis in the same issue of scienceswhich highlights the limitations of the study. “The skills observed are not natural behaviors: they are conditioned by extrinsic rewards, not the seemingly intrinsic ones that humans experience when they follow rhythms,” he wrote with musicologist Gavin Stingo. He compares it to one person trained to ride a bicycle: “Studying this process will not discover the hidden ability of one person to ride a bicycle, but will simply show how this conditioning can cause him to adopt a human skill acquired through cultural evolution.”
Merchant recognizes this nuance, but there is another nuance that is very relevant: “Monos don’t dance to the sound of music as a natural behaviour, it’s not part of their behavioral repertoire. It’s not a completely spontaneous activity, but all the vocal motor machinery needed to generate this complex behavior is in it.”
The authors propose the “four-component hypothesis,” which suggests that musical rhythm synchronization requires the coordination of four processes: an auditory system that extracts complex patterns, a predictive internal clock, a motor system that responds in a proactive manner, and, most importantly, a reward circuit. “With humans, you’re not just ‘very good,’ but ‘this is nice, I like it a lot.'” “There’s an element of pleasure that doesn’t exist in the human case,” Merchant explains.
Next steps: from laboratory to clinic
“We spent at least a few years working together to try to understand everyone,” Merchant explains. For him, the importance of this work lies in the presence of an animal model that allows us to study complex processes in a brain similar to that of a human. Meanwhile, Rajendran, who is running his own laboratory after completing this work, is interested in the clinical implications: “There are diseases that have to do with the vocal motor system.” He mentions, for example, a treatment against Parkinson’s disease that involves putting music on patients, and it is effective: “But, why when listening to music can you suddenly walk, can you dance, when before you had a big brain and it was difficult for you to move? What is the relationship between the auditory and motor systems? We don’t know that, and I think that this kind of work can help a lot in understanding how this disease works,” he emphasizes.
Researchers realize that monkeys do not experience music in the same way as humans. The difference between humans, who have not been trained to enjoy music, requires months of conditioning. But it opens new ways of understanding the development of music and the brain mechanisms that support it, with implications ranging from understanding neurological diseases to demonstrating that it is never too late to learn to play an instrument.