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If some of my colleagues were skeptical of my ambitions to teach a gorilla sign language, it was partly because of the gorilla's reputation for being ferocious, stubborn, and stupid. While chimps have traditionally been the teacher's pet of the behavioral sciences, the rare, self-absorbed gorilla has been given a wide berth by scientists mindful of the animal's strength. Throughout the century timorous researchers have justified this neglect by reciting like a catechism a literature on the animal's intractable nature and dubious intelligence. The gorilla, as every reader knows, has not had a good press. Part of its problem is that the gorilla does not have much documented history. Creditable sightings only date from the mid-nineteenth century. Early accounts spoke of the animal's ferocity and enormous strength. One hunter reported that an enraged gorilla grabbed his gun and crushed the barrel with his teeth. The French-American explorer Paul du Chaillu probably did most to create the popular image of gorillas that still persists today. Du Chaillu caught the public imagination with his lurid description of a gorilla kill in 1861: "His eyes began to flash fiercer fire as we stood motionless on the defensive, and the crest of short hair which stands on his forehead began to twitch rapidly up and down, while his powerful fangs were shown as he again sent forth a thunderous roar. And now he truly reminded me of nothing but some hellish dream creature - a being of that hideous order, half-man half-beast, which we find pictured by old artists in some representations of the infernal regions..." The legacy of such reports shows in a recent poll of British schoolchildren: gorillas ranked with rats and spiders as the most hated and feared creatures on earth. Given the gorilla's awesome image, many people asked me how I would dare to enter the cage of an animal that so terrorized the brutish hunters of the last century. For one thing, I had read another body of scientific literature that described an entirely different animal from the hellish creature of the popular accounts (although even some scientific writings fell prey to superficial prejudices based on the gorilla's appearance). According to George Schaller and Dian Fossey, who have studied gorillas in the wild, they are peace-loving vegetarians despite displays they may use to greet intruders. They roam the forests of Central Africa in nomadic bands of some two to thirty individuals led by a dominant older male. Their communication consists of a combination of postures, gestures, and vocalizations. A sideways glance and an annoyance bark from the dominant male are usually enough to resolve disputes; a grunt or purring vocalization indicates contentment and social harmony. The life span of gorillas in the wild is not known; conservative estimates place it at thirty. In captivity gorillas have been known to reach fifty. In physical development, a ten-year-old gorilla is roughly equivalent to a twelve-to-fifteen-year-old human. Although females are willing to mate from about age seven to nine in the wild (about six in captivity), they usually do not conceive until age ten or eleven (seven to ten in captivity). Males are ready to mate at about age nine or ten. The female often initiates courtship when she is in estrous, and the male usually indicates interest only then. Gorillas in the wild tend to spend much of their time lolling about, eating several times a day from a ready supply of vegetation; and, except for man, they have no enemies. These firsthand reports of the gorilla's gentle nature, along with the photographs Carroll Soo Hoo had often shown me of himself roughhousing with Bwana and other 200-pound gorillas, were enough to still any doubts I might have entertained about the dangers of working with Koko. Contrary to its popular image, the gorilla is less aggressive, less excitable, and in some ways a good deal easier to work with than I had anticipated. That this is not better known is partly because the gorilla is very difficult to obtain for research. But I suspect that many researchers would rather not risk giving a 400-pound animal the benefit of the doubt that is necessary to find out what the animal is really like. Most, if given a choice, would probably prefer to work with chimps, who genuinely seem to enjoy the company of humans. Roger Fouts, a psychologist who has extensively studied chimp use of sign language, remarked that he did not like the way gorillas hunker down at a forty-five-degree angle, turn their heads, and stare sideways at him. Because so little work has been done with gorillas, they have been unfairly regarded as an intellectually disadvantaged, moody, and uncooperative poor relation of the great apes. Gorillas are great apes, a term that refers to the family Pongidae, or pongids. It includes the orangutan (Pongo), the chimpanzee (Pan), and the gorilla (Gorilla gorilla). The orang, or red ape, is a native of Borneo and Sumatra, while the chimp and gorilla are now found only in an ever-diminishing band that runs through equatorial Africa. All three are threatened in the wild by habitat destruction, hunting, and what is euphemistically called "collection" for zoos and laboratories. There are only some 250 mountain gorillas left in existence; lowland gorillas number fewer than 5,000 and 10,000. It is unknown whether the gorilla was ever particularly abundant, but its existence, in spite of recent laws to protect it, is now possibly the most precarious of all the great apes. Together with the lesser apes (the gibbons and the siamang) and man, the great apes are members of the superfamily Hominoidea. Hominoidea, in turn, is a part of the suborder Simiae of the order Primates. Scientists have long debated over which of the great apes is man's closest relative. Depending on whom you talk to and what aspect of the ape's physiology is being examined, researchers make varying claims for the chimp or the gorilla. Adding to this confusion is the assertion by some scientists that the orangutan's brain most closely resembles man's in certain anatomical ways related to the evolution of language. This is somewhat surprising, because the orang is commonly regarded as man's most distant relative among the great apes. For the moment, the question of which ape is most closely related to man will have to be considered open because of the lack of comparative data. Also unsettled is the issue of which great ape is the most intelligent. Such a question is somewhat charged, since we would hardly be comfortable if our closest relative turned out to be somewhat of a dolt compared with the other two. For a long time it was generally assumed that the chimp was the brightest, although there is little hard data to back this up. In fact, as people are asked how they know the chimp is bright, many will cite the descriptive tag on the chimp cage at the zoo. Because we consider the chimp our closest relative, we have tended to accept its intellectual superiority over the gorilla without too much scrutiny. And since chimps are the easiest of the three great apes to test for intelligence, the claim tends to become a self-fulfilling prophecy. Before Project Koko got underway, Duane Rumbaugh administered a series of tests to determine the relative intelligence of a group of chimps, orangs, gorillas, and a pygmy chimp. The tests were inconclusive. One orang consistently had the highest scores. But Rumbaugh wondered how significant the gorilla's low scores were, since it frequently disrupted the test and ultimately crashed the test apparatus. Later learning tests were more conclusive. Required to discriminate between different objects according to varying criteria, the gorilla and orang both performed better than the chimp. Rumbaugh believed that his data had at least exploded the myth of chimp intellectual superiority among the great apes. He remarked that the difference in mechanical aptitudes, or simply in how the animals felt on a particular day, may have had a lot to do with the differences in their performance. (To this observation I say amen.) Rumbaugh noted that vocabulary size would probably be the most reliable measure of intelligence, but since he conducted these tests before it was believed that the apes might develop any vocabulary at all, he had to conclude ruefully that the question was, for the time being, moot. The breakthrough in communicating with chimps, orangs, and gorillas has fostered a renaissance in the study of ape intelligence. I will come back to the issue of intelligence later. It was probably because of behavior like that of Rumbaugh's gorilla destroying the test apparatus that the gorilla developed its reputation as difficult. Two researchers, Hilda Knobloch and Benjamin Pasamanick, went so far as to claim that the gorilla was uncooperative because it was stupid: "There is little question the chimpanzee is capable of conceptualization and abstraction that is beyond the abilities of the gorilla. It is precisely because of these limitations, which are apparently genetically determined...that it is more difficult to work with them." The great primatologist Robert Yerkes shared some of these feelings, but he also suspected that the gorilla's intransigence might indicate the presence of intelligence rather than its absence. In 1925 he wrote, "In degree of docility and good nature the gorilla is so far inferior to the chimpanzee that it is not likely to usurp the latter's place...in scientific laboratories." It also occurred to Yerkes that the gorilla was "a natural experiment in which the value of brawn versus brain is being determined." Ultimately, however, Yerke's clearheaded understanding of his beloved apes led him to observe, "It is entirely possible that the gorilla, while being distinctly inferior to the chimpanzee in ability to use and fashion implements and operate mechanisms, is superior to it in other modes of behavioral adaptation and may indeed possess a higher order of intelligence than any other existing anthropoid ape." Today, more than fifty years after Yerkes made his remark, Koko's performance bolsters his intuition. |
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