Is it possible to teach a chimpanzee how to communicate with humans?
With stories of "feral children" being reported in India and the popularity of books such as Rudyard Kipling's The Jungle Book and Edgar Rice Burroughs' Tarzan of the Apes, the prospect of teaching language skills to chimpanzees or orangutans didn't seem so far-fetched during the 1920s and 1930s. While early research by such pioneers as Russian primatologist Nadiya Ladygina-Kohts and American psychologist Lightmer Witmer helped demonstrate the innate problem-solving skills of chimpanzees, they also raised intriguing speculations about whether true communication between humans and non-humans might be possible.
In 1912, it had been Witmer who publicly suggested that "within a few years chimpanzees will be taken early in life and subjected for purposes of scientific investigation to a course or procedure more closely resembling that which is accorded the human child." But could raising a young chimpanzee in the same way that human children were raised lead to their developing actual language skills? This was the question that Winthrop and Luella Kellogg would test in a very personal way.
Inspired by stories about Kamala and Amala, the two "wolf-girls" who had been reported in India not long before, Winthrop Kellogg, a newly-hired as a psychology professor at Indiana University, approached Yale primatologist Robert Yerkes with a unique research proposal in 1930. By placing an infant ape (whether chimpanzee or orangutan) in a human home and raising that ape alongside a human child of the same age, Kellogg argued that the ape could be socialized like a human and develop language skills.
To make their experiment as realistic as possible, the Kelloggs convinced Yerkes to allow them to conduct their research at the Yale Anthropoid Research Station in Orange Park, Florida. Established in 1930 and operated by Yale University, the station was one of the main primate research facilities in the United States and had an international reputation for groundbreaking research. Later rechristened the Yerkes National Primate Center and relocated to Emory University in Georgia, the station was ideal for what the Kelloggs were planning since it had all the facilities they would need. To fund their research project, the Kelloggs took a leave of absence from Indiana University and arranged for a grant from the Social Science Research Council during their stay in Orange Park.
The first research subject in the Kelloggs' study happened to be their infant son Donald who was born on August 31, 1930. All that remained was to get a suitable infant chimpanzee. In mid-1931, the Kelloggs received their other research subject. Gua, an infant chimpanzee, was born in Cuba's Abreu Colony on November 15, 1930 and subsequently shipped to the Yale Station to become part of their permanent collection. For the course of the planned study, which was intended to cover the first few years of their lives, Donald and Gua would be raised together as siblings so the Kelloggs could monitor how they both developed.
What followed was what Winthrop Kellogg would later describe as one of the most difficult research projects he and his wife had ever attempted. "Had we at that time any knowledge of the personal deprivation to be demanded by the undertaking, it is doubtful if we would have persisted further in the endeavor to bring it about," he wrote, ruefully. Not only were they first-time parents, but their experience in raising a chimpanzee was largely theoretical at that point.
"Let us suppose," the Kelloggs wrote, in their later book describing their experiment, "that by some queer accident a human infant, the child of civilized parents, were abandoned in the woods or jungle where it has had as companions only wild animals. [The comparison to the fictional Tarzan is evident.] Suppose, further, that by some miraculous combination of circumstances it did not die, but survived babyhood and early childhood, and grew up in these surroundings. What would be the nature of the resulting individual who had matured under such unusual conditions, without clothing, without human language, and without association with others of its kind? That this is not so fanciful a conception as to lie altogether outside the realm of possibility is attested by the fact that about a dozen instances of "wild" foundlings of this sort are known to history. To be sure the reports about them are in many cases so garbled and distorted that the true facts are hard to shift out. In some, however, the accuracy of the accounts is well established."
In providing Gua with the kind of social development human children normally received, the Kelloggs hoped to disprove many of the genetic theories of human behaviour that were already being used to justify the appalling eugenic policies being advocated across the United States. Instead, Winthrop Kellogg had a more optimistic view about human nature which he discussed in his book:
"It would be quite possible according to the latter view to take the child of criminal delinquents, provided he was normal at birth, and by giving him the proper training, to make him a great religious or moral leader. Conversely it would be possible to take the child of gifted and upright parents and by placing him in a suitable environment, to produce a criminal of the lowest order. Heredity, in this view, assumes a secondary role and education or training becomes the important item."
Much like John B. Watson and other behaviourists, the Kelloggs insisted that upbringing played an essential role in shaping human development. While they knew there were limits to how far Gua could progress even if raised like a human child, they did hope to prove that an infant chimpanzee could acquire language skills if the training began early enough.
Being practical experimenters, the Kelloggs began by taking measurements for both Donald and Gua - height, weight, blood pressure, etc. Gua was rated as having the bone structure of a human child twice her age with sixteen of her "baby teeth" at the time she was separated from her mother. In many ways, she was far in advance of Donald who was a typical human baby with limited motor development. They then placed both their infants on a daily schedule including waking up at 7 AM, getting their breakfast, sitting in identical high chairs while the adults were having breakfast, then regular play sessions and naps (Donald needed more nap time than Gua).
Both infants received an identical diet including warm milk, cereal, orange juice, and fruit. There were still a few differences in their diets considering Gua's fondness for eating insects as well as flowers and the leaves of some plants (Donald was a little more particular about what he ate). Though the Kelloggs noted other differences between Donald and Gua which became more evident over time, they did their best to provide both infants with the same learning opportunities. They even had a special walker made for Gua which matched the walker used by Donald though Gua never used it for walking the way Donald did.
In the months that followed, the Kellloggs would carefully record everything they learned about their two subjects. While Gua never mastered language the way they had hoped, what the Kelloggs eventually discovered would help rewrite everything psychologists thought they knew about how humans and non-humans developed
Raising an infant chimpanzee the human way is not an easy thing to do.
Aside from Gua's fondness for insects, flowers, and whatever else she could stick in her mouth, she was also much more active than her "brother" Donald. Being constantly thirsty, she became a frequent user of water faucets after learning how a water tap worked. She also enjoyed baths, except for her tendency to eat the soap, and enjoyed sleeping in a regular bed. Once, when the bed was removed for cleaning, Gua cried until it was returned. As for how they behaved while sleeping, the Kelloggs reported that both Donald and Gua looked and acted much the same when sleeping at night including having the same posture and acting the same way on awakening.
But there were still important differences between Donald and Gua. When it came to picking up a piece of food, for example, Gua often used her mouth since she was incapable of grasping with her hand the way Donald could. Even when the Kelloggs tried to teach her to grasp objects with her hands, she was often clumsy due to lacking an opposable thumb. Gua also had trouble with building blocks since she didn't have the motor precision of a human child
In terms of learning to walk, there were other important differences. Donald took to using his walker to get around and was often "reckless" in trying to walk without it. As for Gua, she never learned to use the walker though she enjoyed being pushed around by someone else. She continued to use the walker as a toy even after learning to walk but there were still marked differences in the walking styles they adopted, however.
By the age of eight months, Gua was responding to her reflection in a mirror and she also noticed changes in her environment much faster than Donald did. At the age of fourteen and a half months, both Donald and Gua were shown a child's alphabet book. Though Gua was faster at attending to visual content, Donald learned to point to a picture that an adult had just indicated. Gua, on the other hand, tried to lift pictures from the page suggesting well-developed depth perception.
Gua's hearing was also much more acute that Donald's (or his human parents) and she often responded to sounds like the newspaper being delivered much sooner than anyone else. When it came to localizing sounds, Donald and Gua showed no real difference that the Kelloggs could determine. Another problem was that Donald could signal that he disliked something he tasted by his facial expressions, something they were never able to achieve with Gua. Not only was Gua's sense of smell much more acute than Donald's, but she also depended on smell to identify people much more than Donald did. Whenever meeting someone for the first time, Gua would smell them first and rely on her sense of smell to recognize everybody she met.
Gua had a number of overwhelming fears during her time with the Kelloggs. She was terrified of being left alone and was often anxious whenever her human parents exited the house. She was also terrified by far-off noises such as planes passing overhead. Other fears came from learned experiences. After a small dog snapped at her when she cornered it, Gua became afraid of small animals. She was also terrified of toadstools after being unintentionally poisoned by one when she ate it. There were also frequent tantrums, especially when Donald received treatment she didn't get.
But she was good at learning to be as human as possible. It took a while but the Kelloggs got her used to being dressed in human clothes and to allowing her nails and teeth to be cleaned. She also picked up toilet training, how to use a light switch, how to eat with a spoon, and how to drink from a glass. Donald and Gua were regularly tested using standard test batteries intended for infants. Though Gua was more advanced than Donald at first, he quickly overtook her. Since the tests were never designed for infant chimpanzees, it is hard to make any firm conclusions about problem-solving or memory. Still, Gua's cognitive development was steadily increasing as a result of her enriched upbringing.
It was trying to teach Gua to speak that generated the most interest from outside observers. Up until that time, the prevailing scientific consensus was that only humans were capable of true speech (as opposed to mimicry seen in parrots and other birds). Since the 19th century, brain researchers had known that the human capacity for language was linked to specific regions of the brain that were largely absent in chimpanzees and other non-human primates. Given their belief in behaviourist theories of language development, the Kelloggs reasoned that Gua could be taught language skills in much the same way that human children were. And this is where the experiment went sour.
Through the course of the Kellogg study, Gua learned to use facial expressions and developed her own hand gestures to express what she wanted. As Winthrop Kellogg later wrote, "Almost from the beginning of her human training, Gua seemed to possess a rudimentary, nonvocal form of communication by means of which her impending actions could be predicted by those who knew her well. " While Robert Yerkes had actually proposed teaching chimpanzees sign language, the Kelloggs focused on actual spoken language in their experiment.
What they found was that Gua was capable of a wide range of articulations and grunts. However, teaching her even simple words like "pa-pa" seemed just about impossible despite repeated efforts. Though not dismissing the possibility of chimpanzee speech completely, they concluded that Gua would never be capable of speaking more than a handful of words. As for whether Gua was successful in learning to understand human language, this is something the Kelloggs simply failed to follow up on. This inability to speak was deeply disappointing to the Kelloggs and may have coloured their impression of the other things that Gua had been successfully taught to do. But it when they saw the effect that all of this was having on Donald that things became, ahem, somewhat hairy.
Though the Kelloggs had originally planned for a five-year study, the research project came to an abrupt end when they realized that Donald was being adversely affected by being raised along with Gua Not only did he begin giving guttural food barks similar to Gua when asking for food, but he also developed the alarming habit of grunting at his parents the way that his "sister" did. It was at this point, just nine months after their research began, that the Kelloggs decided that the experiment needed to be terminated.
As Winthrop Kellogg later wrote:
The situation in which the two lived together as playmates and associates was much like that of the two-child family in which Gua, because of her greater maturity and agility, played the part of the older child. With the added stimulation thus afforded, the younger child in such situations usually learns more rapidly than would otherwise be the case. It was Gua, in fact, who was almost always the aggressor or leader in finding new toys to play with and new methods of play; while the human was inclined to take up the role of the imitator and follower.
Still, by the time the Kelloggs terminated their experiment, Gua had made amazing progress. She had learned to walk upright and respond to over twenty different commands, including "Shake hands" and "Open the door" (Donald had only learned three by this point). Despite her progress however, Winthrop and Luella Kellogg had grave doubts about what was Gua was actually learning. As they later commented:
"Let us consider finally the ability of the subjects [apes] in the comprehension of language. We are here faced, as in many earlier instances, with the problem of inner mental processes, for we cannot tell in a strict usage of the term whether the subjects introspectively comprehend what is said about them or not. All we can do is to observe whether they are able to react distinctively and individually to separate words and phrases. This, then, must serve as our criterion of 'comprehension.'
Still, while Donald was outperforming Gua in many other ways, including the spontaneous use of language, Gua's progress could not be doubted. What she learned while raised as a human would shatter many of the assumptions previously made about the differences between humans and non-humans.
Which still raised the question of how successful Gua could be in becoming readjusted to life among other research chimpanzees after living most of her life separated from other of her own kind. The Kelloggs did their best to prepare Gua for her return to living with other chimpanzees at the primate centre in Florida. However, the transition was likely traumatic considering they were the only real parents Gua ever knew. I haven't been able to determine anything of Gua's life at the primate centre except that Robert and Ada Yerkes continued to use Gua in their own chimpanzee research. For whatever reason, Gua didn't live long after the Kelloggs returned to Indiana. She died of pneumonia on December 21, 1933, less than a year after being separated from her "brother" and the loving care she received with the Kelloggs. Her death so soon afterward represents a tragic (and little-mentioned) footnote in what is otherwise hailed as a classic study in human-ape communication.
As for Winthrop and Luella Kellogg, their 1933 book, The Ape and the Child, became an instant classic. One reviewer described it as a "well-written, mature, and scholarly piece of psychological literature." The reviewer went on to say that it should be "required reading in all courses where the problem of heredity and environment is discussed." Not surprisingly, the Kellogg study generated enormous publicity with stories about Donald and Gua being written in the New York Times and other popular newspapers. Video clips from their life together are still available online.
It's hard to say how much of an impact the Kellogg study actually had on the eugenics movement (which was already dying out in the United States due to revelations over what was happening in Nazi Germany) as well as the entire heredity vs. environment debate. Still, what Winthrop and Luella attempted to do inspired other researchers to try similar studies. During the 1950s, psychologists Keith and Catherine Hayes launched their own experiment in raising a chimpanzee named Viki as a human child. They even managed to train Viki to speak four English words after extensive speech therapy though the barrier to full human speech seems impassable.
Of course, the most well-known experiment of its kind was Allen and Beatrix Gardner's work during the 1960s and 1970s teaching American Sign Language (ASL) to a chimpanzee named Washoe. Not only did Washoe manage to learn hundred of ASL words, she even taught some ASL to her own son, Louis. Though this work is still controversial, the Gardners' success with Washoe and other chimpanzees helped revive interest in animal communication as well as the biological roots of language. Similar work with a gorilla named Koko has reportedly led to her learning as many as one thousand words in a modified version of ASL. Again, the research results evaluating Koko's progress continues to spark controversy.
As for Winthrop Kellogg, he went on to become one of the pioneers in animal research for much of his long career as a psychologist. Having moved to Florida State University in 1950, he was instrumental in reshaping the psychology program there and also became part of Florida State's marine research laboratory. Though his later research would never be as famous as what he had tried to do with Gua, he also became one of the first researchers to study how bottlenose dolphins use sonar to navigate as well as exploring dolphin communication and problem-solving ability. This involved inventing a special dolphin pool for use in research as well as becoming a scuba diver himself to explore the research environment from the point of view of the dolphin. He would later attempt to apply what he had learned about echolocation in dolphins to help blind humans navigate.
Even in retirement, Winthrop Kellogg stayed active in research including directing graduate students looking at cognitive ability in sea lions. He died in the summer of 1972, ten years after formally retiring from teaching. His wife Luella died just a few months later and, tragically, their son Donald died in the following year.