In a talk on “Gestural Communication and Pantomime in Great Apes” March 6 in Cornell's Goldwin Smith Hall, evolutionary anthropologist Itai Roffman from the University of Haifa and three Cornell faculty respondents explored the implications of the latest findings on primate culture and communication.
“This is profound and deeply moving research. It raises questions that by definition cannot be contained by any single science or discipline,” said co-organizer Cathy Caruth, Frank H. T. Rhodes Professor of Humane Letters in the Departments of English and Comparative Literature.
Roffman is the only researcher to have extensively studied, with a comparative perspective, the cognitive and communicational abilities of chimpanzees and bonobos living in a natural environment (in Mali), captive environments like zoos and sanctuaries, and the Pan/Homo [chimpanzee/human] symbolic cross-culture in primatologist Sue Savage-Rumbaugh’s lab, noted co-organizer Laurent Dubreuil, professor of Romance studies, comparative literature and cognitive science.
Genetically, chimpanzees are a sister species to humans, said, Roffman, with 98.8 percent of our DNA identical. “Chimps are closer to humans than they are to gorillas and orangutans, which has moral and social implications,” he said. “Their facial expressions, survival strategies, body language and a whole suite of traits are similar to ours. We don’t need to look at the stars for aliens; we have intelligent non-human life here on earth.”
Roffman compared chimps, with their meaningful informational exchange and tool-making capabilities, to early hominin species, noting that their meaningful mark making and referential imagery is comparable to early cave paintings. “Chimps are living fossils. In Mali captive chimpanzees walk bipedally up to 50 percent of the time. They extend their knees just like Homo habilis, and not like other chimps – this is the plasticity of genes,” said Roffman. “The chimps in Mali use stone tools just like Lucy did 2 million years ago. They inhabit cliff-dwellings, build diverse nest types, including bamboo dome shaped constructions with nests over them, thus exhibiting proto-architectural competencies. They also use bamboo to mark their trails and make junctions and in so doing map their territories.”
Chimpanzees have cultural diversity and each group has its own unique customs, rules and norms, said Roffman. Significantly, he and other researchers have found that nonhuman hominids (great apes) can remember experiences across time and talk about things that happened in the past, a requirement for giving valid testimony in a court of law.
In his response, Harry W. Greene, Cornell professor emeritus of ecology and evolutionary biology and a Stephen H. Weiss Presidential Fellow, raised questions about the ancestral characteristics of the evolutionary group that includes humans, chimps and bonobos, a topic he explored in “Evolutionary Scenarios and Primate Natural History,” published in 2017 in the American Naturalist.
“Archaeology has found material culture for three species other than human: chimps, capuchin monkeys in Brazil and long-tailed macaques,” he said. “We’ve found percussive tools made by chimps 4,000 years ago.”
Greene exhibited a spear, fashioned intentionally with a sharpened point, which was used by chimps to spear bushbabies. “The spear has evolved three times, once in our lineage and once by chimps, and once by capuchin monkeys to go after snakes,” he said.
In his response, Morten Christiansen, the William R. Kenan, Jr. Professor of Psychology and co-director of cognitive science, focused on how humans process and acquire language. “The brain doesn’t have a specialized language system,” he said. “Language piggy backs on many evolutionarily older systems in the brain.” Language has been adapted to the specifics of our brains, he said, adding that “we should therefore not expect other species to easily pick up on human language because it may not fit the peculiarities of their brains.”
Christiansen pointed out that humans have an average vocabulary of 60,000 words, but that a mere 200 words account for 80% of what we say to children. The bonobos in Savage-Rumbaugh’s lab have learned 423 lexigrams with which to communicate, so that “bonobos may in many cases have a more complex conversation than you have with your kids,” said Christiansen.
“We, humans, like to think of ourselves as special but we’ve learned that this is not really the case,” he said. “In the last few decades, we’ve come to rethink Neanderthal abilities. They had complex representational art, buried their dead, and appear to have been on a par with modern humans in most respects, perhaps including language – so language is older than just us.”
In his response, Dubreuil said that the vocal repertoire of nonhuman great apes is still dramatically undervalued. Despite mounting evidence that the bonobos raised by Savage-Rumbaugh were trying to utter words with their mouth (they can speak only in vowels, not consonants), attempts at human-like vocalizations in bonobos have not been satisfactorily deciphered. ”But the gestural repertoire of bonobos and chimpanzees has formed a new topic of inquiry,” he said, citing “The Great Ape Dictionary,” that has identified several dozen gestures that are intentionally selected and apparently convey meaning.
“The few features of the vast, and certainly culturally defined, gestural repertoire in bonobos and chimps that have been deciphered already indicate, in great apes, a capacity to share desires, actions or requests through gestures -- as well as an aptitude to make their ‘body language’ iconic,” said Dubreuil. “This strengthens the possibility for such aptitudes to have been present, at least in some form, in our last common ancestor, roughly 5 million years ago.”
Dubreuil also stressed that "the study of meaningful gestures should move away from the mechanical and linear schema of information transmission, and put the emphasis on semantic embedding."
During the lively discussion following the responses, Andy Bass, professor of neurobiology and behavior, pointed out that cetaceans, too, show evidence of vocal learning. “All animals communicate with each other,” he said. “I’m interested in fish because we have basic attributes that we share with them: the fundamental principles on which the brain is organized. I can explain the basic structures in the brains of fishes that leads to gestural communication.”
The March 6 event was part of a larger series of transdisciplinary activities at Cornell focused on communication in human and nonhuman animals, which has included the Eloquence of the Apes workshop in October; a class on Culture, Cognition and the Humanities taught by Dubreiul and Christiansen; a project documenting the experiences of those working in close relation to nonhuman primates, through video testimonies; and work on founding an institute for language studies at Cornell.
“The institute would be about the building blocks of what makes us ‘human,’ and mainly, language and culture,” explained Dubreuil. “Our intellectual ambition is to foster meaningful dialogues (and not simply collaborations) involving scientists, social scientists and humanists. We do not believe that a discussion about ’human language’ belongs to one particular discipline, or that it could exclude from its focus the study of animal communication or considerations about the art of poetry…The enthusiasm that the current event created is a wonderful sign, I believe, of the sort of scholarly integration we could look for at Cornell.”