Reiss’s research on dolphin cognition is one of a handful of projects on animal communication that dates back to the 1980s, when there were widespread funding cuts in the field, after a top researcher retracted his much-hyped claim that a chimpanzee could be trained to use sign language to converse with humans. In a study published in 1993, Reiss offered bottlenose dolphins at a facility in Northern California an underwater keypad that allowed them to choose specific toys, which it delivered while emitting computer-generated whistles, like a kind of vending machine. The dolphins spontaneously began mimicking the computer-generated whistles when they played independently with the corresponding toy, like kids tossing a ball and naming it “ball, ball, ball,” Reiss told me. “The behavior,” Reiss said, “was strikingly similar to the early stages of language acquisition in children.”
The researchers hoped to replicate the method by outfitting an octopus tank with an interactive platform of some kind and observing how the octopus engaged with it. But it was unclear whether such a device might interest the lone cephalopod. An earlier episode of displeasure led her to discharge enough ink to turn her tank water so black that she couldn’t be seen. Unlocking her communicative abilities might require that she consider the scientists as fascinating as they did her.
While experimenting with animals trapped in cages and tanks can reveal their latent faculties, figuring out the range of what animals are communicating to one another requires spying on them in the wild. Past studies often conflated general communication, in which individuals extract meaning from signals sent by other individuals, with language’s more specific, flexible and open-ended system. In a seminal 1980 study, for example, the primatologists Robert Seyfarth and Dorothy Cheney used the “playback” technique to decode the meaning of alarm calls issued by vervet monkeys at Amboseli National Park in Kenya. When a recording of the barklike calls emitted by a vervet encountering a leopard was played back to other vervets, it sent them scampering into the trees. Recordings of the low grunts of a vervet who spotted an eagle led other vervets to look up into the sky; recordings of the high-pitched chutters emitted by a vervet upon noticing a python caused them to scan the ground.
At the time, The New York Times ran a front-page story heralding the discovery of a “rudimentary ‘language’” in vervet monkeys. But critics objected that the calls might not have any properties of language at all. Instead of being intentional messages to communicate meaning to others, the calls might be involuntary, emotion-driven sounds, like the cry of a hungry baby. Such involuntary expressions can transmit rich information to listeners, but unlike words and sentences, they don’t allow for discussion of things separated by time and space. The barks of a vervet in the throes of leopard-induced terror could alert other vervets to the presence of a leopard — but couldn’t provide any way to talk about, say, “the really smelly leopard who showed up at the ravine yesterday morning.”
Toshitaka Suzuki, an ethologist at the University of Tokyo who describes himself as an animal linguist, struck upon a method to disambiguate intentional calls from involuntary ones while soaking in a bath one day. When we spoke over Zoom, he showed me an image of a fluffy cloud. “If you hear the word ‘dog,’ you might see a dog,” he pointed out, as I gazed at the white mass. “If you hear the word ‘cat,’ you might see a cat.” That, he said, marks the difference between a word and a sound. “Words influence how we see objects,” he said. “Sounds do not.” Using playback studies, Suzuki determined that Japanese tits, songbirds that live in East Asian forests and that he has studied for more than 15 years, emit a special vocalization when they encounter snakes. When other Japanese tits heard a recording of the vocalization, which Suzuki dubbed the “jar jar” call, they searched the ground, as if looking for a snake. To determine whether “jar jar” meant “snake” in Japanese tit, he added another element to his experiments: an eight-inch stick, which he dragged along the surface of a tree using hidden strings. Usually, Suzuki found, the birds ignored the stick. It was, by his analogy, a passing cloud. But then he played a recording of the “jar jar” call. In that case, the stick seemed to take on new significance: The birds approached the stick, as if examining whether it was, in fact, a snake. Like a word, the “jar jar” call had changed their perception.