On August 24, 1661, Samuel Pepys, an administrator in England’s navy and famous diarist, took a break from work to go see a “ strange creature ” that had just arrived on a ship from West Africa. Most likely, it was a chimpanzee—the first Pepys had ever seen. As he wrote in his diary, the “great baboon” was so human-like that he wondered if it were not the offspring of a man and a “she-baboon.”
“I do believe that it already understands much English,” he continued, “and I am of the mind it might be taught to speak or make signs.”
Humans and apes share nearly 99% of the same DNA, but language is one thing that seems to irreconcilably differentiate our species. Is that by necessity of nature, though, or simply a question of nurture?
“It could be that there’s something biologically different in our genome, something that’s changed since we split from apes, and that’s language,” says Catherine Hobaiter, a primatologist at the University of St. Andrews in Scotland. “But another possibility is that they might have the cognitive capacity for language, but they’re not able to physically express it like we do.”
In the centuries since Pepys’ speculations, scientists and the public alike have only become more enamored with the idea of breaking through communication barriers separating our species. “It’s every scientist’s dream,” Hobaiter says. “Instead of having to do years of tests, we could just sit down and have a chat.”
Hobaiter’s work shows that chimps have their own rich world of communication—it’s sort of like a secret sign language.
This not only would allow us to find out what our closest relatives are thinking, but also to potentially learn something about our own evolution and what it means to be human, says Jared Taglialatela, an associate professor at Kennesaw State University and the director of research at the Ape Cognition and Conservation Initiative. “We shared a common ancestor just 5.5 million years ago with both chimpanzees and bonobos,” he says. “That’s useful for making comparisons and answering questions about human origins.”
Apes and humans are even more similar than we ever imagined.
Scientists have been trying to teach chimps to speak for decades, with efforts ranging from misguided to tantalizingly promising. Now, however, they are coming to realize that we’ve likely been going about it in the wrong way. Rather than force apes to learn our language, we should be learning theirs.
Researchers have only just begun to understand the rudimentary fundamentals of ape communication, but already the results are exceeding expectations. Apes and humans, they are discovering, are even more similar than we ever imagined.
“Pretty much all of the capacities we thought of as being uniquely human—learning socially, using communication to reach a goal, shifting our communication depending on who we’re communicating with, being able to plan for the future, keeping record of friends and enemies—actually are not,” Hobaiter says. “They’re all present in chimps.”
All in the Family
The story of modern research into ape communication begins in 1931, when Winthrop and Luella Kellogg, a husband-wife psychologist team, decided to raise a chimp named Gua alongside their biological son, Donald. The goal was to see if Gua would pick up language, just as a human child would. The landmark experiment inspired many similar efforts—but research with Gua herself lasted less than a year. She was failing to pick up language. (Donald, on the other hand, was reportedly making chimpanzee sounds.) So the Kelloggs called it quits and gave her to a primate center. Less than a year later, she died from pneumonia.
Similar sorts of real-life Curious George projects continued in the 1940s and 1950s, when another husband-wife team, Keith and Catherine Hayes, tried to teach a chimp named Viki spoken human language. After several years, Viki could only use four words: mama, papa, cup, and up. The experiment was cut short when Viki died of meningitis at the age of seven, but many interpreted her lack of progress to mean that apes were not capable of sophisticated communication.
Shortly after the Viki experiment ended, however, Jane Goodall’s groundbreaking research on chimpanzees began to hit the news. Goodall showed that chimps are highly intelligent, emotional beings with individual personalities and capable of constructing tools—discoveries that challenged assumptions about their limited abilities.
In 1967—the year before Planet of the Apes was released—yet another husband-wife team, Allen and Beatrix Gardner, decided to give communication experiments another try. But they went with a different approach: rather than spoken language, they would teach a chimpanzee named Washoe American sign language. Washoe—who wore clothes, sat at the dinner table, brushed her teeth and played games—quickly began to learn and seemed to understand the meaning of the signs. A few years into the project, the Gardners moved on to other work and gave their adopted chimp daughter to a primate center. But scientists there continued to work with Washoe, and by the end of her life, she had learned around 250 signs and had even taught her son to sign.
Sign language, researchers agreed, seemed the way to go. Nim Chimpsky, another chimp raised by a human family in the 1970s and taught to sign, showed similar progress—as did Koko, the gorilla who understood more than 1,000 signs of “Gorilla Sign Language” (GSL) and was exposed to English at an early age. But the work on Nim was cut short when Nim’s adopted father and experimenter, Herbert Terrace, became convinced that Nim had not learned sign language at all, but had rather been imitating the trainers. Terrace abandoned Nim—who continued to try to sign for the rest of his days—to a life of animal testing, cages, and solitude.
Nim’s sad end also cast doubt on whether Washoe had in fact learned to sign. “Debate went back and forth about Nim Chimpsky and others, and the whole field began to implode,” Hobaiter says. “But that also coincided very much with the animal rights movement, and the idea of growing awareness that apes are extraordinary individuals.”
Indeed, some researchers were not ready to give up, and they decided to try yet another approach. In the mid-1970s, Emory University scientists created a symbol board—essentially, a primitive computer—and taught a chimp named Lana to string together different keys to mean different things. Spinning off from there, primatologists discovered what is likely the most talented ape of them all, a bonobo named Kanzi.
Kanzi, who currently lives at the Ape Cognition and Conservation Initiative in Iowa, learned to communicate by observing scientists trying to teach his mother. “Kanzi basically surprised everyone when he started using the symbols on the board,” Taglialatela says. “Not only that, he seemed to be showing proficiency for understanding spoken language that researchers were just using around the apes while trying to train them.”
By 1993, Kanzi could pass rigorous language comprehension tests, performing at about the level of a 3.5-year-old human child. In controlled tests, he shows proficiency in about 90 symbols, and his keepers say he can use around 250 symbols in more natural environments. He also seems to understand complex sentences: In one experiment , he correctly responded to three-quarters of 660 spoken instructions.
Kanzi is no doubt an exceptionally intelligent individual. But researchers continued to wonder whether his knack for communication was a result of his time with humans—or represented a deeper ability, something that scientists, until now, have overlooked. In trying to force apes to learn our language, have may we blinded ourselves to theirs.
Into the Wild
Researchers continue to work with captive apes to try to answer questions about how they communicate with one another and how that relates to the complexity of their social and emotional lives. But focus is also increasingly turning to directly observing apes in their natural environment. As Hobaiter says, “If we want to know if humans are unique in our language use, we must look at what apes are doing naturally.”
While some researchers attempt experimental studies in the field, Hobaiter prefers a fly-on-the-wall approach. For the past 11 years, she has stalked her subjects—a group of chimpanzees in Uganda—in the most unobtrusive way possible, allowing them to slowly get used to her. She videotapes their interactions and later analyzes the recordings, noting every gestures the chimps make while also trying to parse the wider social context in which individuals are interacting.
“If we want to know if humans are unique in our language use, we must look at what apes are doing naturally.”
Like humans—who regularly communicate with a simultaneous mix of spoken words, tone, facial expressions, and gestures—Hobaiter and other researchers have found that apes seem to use concurrent modalities, or different, overlapping means of getting their point across. It’s a discovery that hints at the complexity of ape communication, but it also makes deciphering seemingly simplistic movements laborious. “If there’s an arm raise gesture, you need to see dozens of cases from dozens of individuals” to fully understand its intent, Hobaiter says. “Like human words with multiple meanings, you need context to know what’s going on in communication.”
So far, she and her colleagues have translated what they believe are the chimps’ basic 60–80 gestures , plus a number of facial expressions and vocalizations. She believes that, together, these things make up ape language phonics. Distilling the meaning of those various sounds and gestures when put together, however, will be a much more challenging and drawn-out task.
“We have this whole system of communication that looks very language-like,” Hobaiter says. “Definitely, we are only beginning to scratch the surface.”