02/20/2026
What is your position?
If you wanted to study how vocalizations interact with qualities like rhythm and tempo, you could watch how an opera singer moves while performing an aria, or how a chorus sways while reciting spirituals. But you could also look at s*x, an activity during which (ahem) rhythms and vocalizations become prominent as the action heats up.
A new study published in Evolution and Human Behavior analyzes s*xual behavior of great apes as part of a broader investigation to better understand “how rhythm, tempo, and vocalization evolved in humans and animals.” Researchers from Italy, Belgium, and Denmark set out to determine the role of facial expressions during s*xual interactions of bonobos (Pan paniscus). As our closest relatives (alongside chimps), bonobos live in groups where s*xuality goes beyond mere reproduction to also serve social functions.
“By comparing their behavior with humans and other species, we hope to better understand which elements of communication are uniquely human and which building blocks are much older in our evolutionary history,” explained study author Elisabetta Palagi, an ethologist at the University of Pisa in Italy, in a press release.
The researchers analyzed video recordings frame-by-frame of a colony of captive bonobos at the Wilhelma Zoologisch-Botanischer Garten in Germany. From 64 hours of footage, they gleaned data on 159 s*xual sessions among 18 individuals. Given the social nature of bonobo s*x, some sessions included multiple partners. The researchers noted whether bonobos made “silent bared-teeth displays” (grin-like expressions common during socio-s*xual interactions), watching for incidences of rapid facial mimicry, where one bonobo grins and s*xual partners follow suit.
By plotting those incidences against the rates of s*xual movements (both pelvic thrusts and grinds), which averaged a rapid seven movements per second, the researchers analyzed the relationship between mutual grinning and the tempo of s*x. They found no correlation, concluding that bared-toothed grins didn’t accelerate or decelerate s*x. However, once the mutual grinning stopped, s*xual movements simmered way down.
Study author Yannick Jadoul, neuroscientist at Sapienza University of Rome, hypothesized that “the sharp decrease in tempo afterward could potentially be linked to physiological processes, such as or**sm. We cannot say that with certainty based purely on observational data, but the pattern is striking.”
Sounds like bonobos may be giving us a window into our own behavior, while offering clues to the evolution of socio-s*xual communication in great apes.
