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Horses possess a phonetic capacity that, until now, had never been documented among large terrestrial mammals. Moreover, according to a recent study published in the journal Current Biology, it challenges the conventionally established laws of biology for this type of animal. The research confirms that these equines emit dual sounds through a sophisticated laryngeal whistling mechanism.
According to the researchers from the University of Copenhagen and the University of Lyon/Saint-Etienne who conducted the study, the horse's neigh is not a simple sound. Rather, it is a complex phenomenon of biphonation where two independent frequencies overlap. While one wave is low-pitched, the other is high-pitched, allowing the animal to transmit different emotional messages simultaneously.
This discovery would break the rules of acoustic allometry. Specifically, this concept establishes the relationship between an animal's body size and the physical characteristics of its vocalizations, that is, the frequency, duration, and intensity of the sounds it emits. As a general rule, body dimensions determine the pitch, but horses manage to break this technical scheme through an evolutionary adaptation unprecedented in zoology.
The mechanics of the neigh
But how did they reach this conclusion? The researchers placed endoscopic cameras on stallions of the Franches-Montagnes breed and analyzed their larynges by introducing helium. The data showed that the low frequency arises from the vibration of the vocal cords, a process similar to speech or singing in humans.
The big surprise lies in the high-pitched component, generated by a laryngeal whistle that works on aerodynamic principles. This dual system had only previously been documented in much smaller species, such as rodents, or in marine mammals like dolphins. Horses thus become the first large terrestrial mammals capable of performing this vocal feat in a combined and constant manner.
Communication also evolves
"Understanding how and why biphonation has evolved is an important step in elucidating the origins of the astonishing diversity of mammalian vocal behavior," David Reby highlighted in statements given to The Guardian. Apparently, the usefulness of this vocal ability would lie in the efficiency of sending complex social information within the herd without needing to make multiple calls.
Unlike donkeys or zebras, which lack this marked high-pitched component, the domestic horse has perfected this communicative tool. Meanwhile, the discovery also opens new avenues in the field of veterinary medicine, as it promises to aid in the diagnosis of laryngeal pathologies simply by analyzing the acoustic purity of the emitted frequencies. (National Geographic) (Photo: Taken from Internet)
