Toshitaka Suzuki, an ethologist at the University of Tokyo and a self-described animal linguist, came up with a way to distinguish intentional calls from involuntary calls while showering in the bathroom one day. When we spoke via Zoom, he showed me a photo of a fluffy cloud. “If you hear the word ‘dog,’ you might see a dog,” he pointed out as I stared at the white mass. “If you hear the word ‘cat,’ you probably see a cat.” He said that this represented the difference between a word and a sound. “Words affect how we see things,” he said. “Sounds no.” Using playback studies, Suzuki determined that Japanese tits, songbirds that live in the forests of East Asia and which he has studied for more than 15 years, Makes a special sound When they encounter snakes. When other Japanese tits heard a recording of the sound, which Suzuki called the “pitcher” call, they searched the ground, as if searching for a snake. He added that it was to determine whether the word “jar jar” means “snake” in Japanese Another element of his experimentsA stick eight inches long, which he drags across the surface of a tree using hidden strings. Suzuki found that the birds usually ignored the stick. It was, by his measure, a passing cloud. But then he played a recording of the “pitcher’s pitcher” call. In this case, the stick seemed to take on a new significance: the birds approached the stick, as if examining whether it was in fact a snake. Like a single word, the call “jar jar” changed their perception.
Cat Hobbiter, a primatologist at the University of St Andrews who works with great apes, has developed a similarly precise method. Because great apes seem to have a relatively limited repertoire of vocalizations, Hopayter studied their gestures. For many years, she and her colleagues tracked chimpanzees in Budongo Forest and gorillas in Bwindi, Uganda, recording their gestures and how others responded to them. “Basically, my job is to get up in the morning and take the chimps when they come out of the tree, or the gorillas when they come out of the nest, and just spend the day with them.” she told me. She says that she has so far recorded about 15,600 cases of gesture exchange between monkeys.
To determine whether these gestures are involuntary or intentional, she uses a method adapted from research conducted on infants. Habiter looks for signals that trigger what she calls an “apparently satisfactory outcome.” The method is based on the theory that involuntary signals continue even after listeners understand their meaning, while intentional signals stop once the sender of the signal realizes that the listener has understood the signal. This is the difference between a hungry child’s constant crying after her parents have gone to get a bottle, and my pleas for you to pour me some coffee, which stops as soon as you start reaching for the coffee pot, Habiter explains. To look for a pattern, she says she and her researchers looked “at hundreds of cases, dozens of gestures, different individuals using the same gesture across different days.” So far, her team’s analysis has limited to video-recorded exchanges spanning 15 years Dozens of monkey gestures Which leads to “apparently satisfactory results.”
These gestures may also be clear to us, although less than our awareness. Habiter applied her technique to 1- and 2-year-old preverbal children, tracking them to record their gestures and how they affected others who were attentive, “as if they were little monkeys, which they basically are,” she says. She also posted short videos of the apes’ gestures online and asked adult visitors who had not spent any time with great apes to guess what they thought they meant. I found it pre-verbal Human children use at least 40 or 50 gestures From the monkeys’ repertoire, adults correctly guessed the meaning of video-recorded monkey gestures at a rate “much higher than would have been expected by chance,” reported Hobaiter and Kirsty E. Graham, a postdoctoral research fellow in the Hopeter lab, wrote in a 2023 PLOS Biology paper.
Emerging research would seem to suggest that there is nothing very special about human language. Other species use word-like intentional signals just as we do. Some, such as Japanese tits and babblers, are known to combine different signals to create new meanings. Many species are socially and culturally transmitted, fulfilling what may be a basic requirement for an organized communication system such as language. However, a stubborn truth remains. Species that use features of language in their communication have few obvious geographic or evolutionary similarities. Despite years of research, no one has discovered a communication system with all the characteristics of language in any species other than our own.