The Ape And The Sushi Master Reflections Of A Primatologist

by Franz De Waal

  To bring these tendencies to bear on the issue of culture, we need only look at how chimpanzees learn to crack oil-palm nuts. According to field-workers, the expertise of their animals far exceeds that of any human who tries it for the first time. It takes many years of practice to place one of the hardest nuts in the world on a level surface, find a good-sized hammer stone, and hit the nut with the right speed so as to crack it. It is the most complex tool-use task known from the field, involving both hands, two tools, and exact coordination.

  A Japanese primatologist, Tetsuro Matsuzawa, carefully tracked the development of this skill in wild chimpanzees at Bossou, Guinea. Young chimpanzees join the rest of the group at the cracking "factory": a location where the apes gather nuts around anvil stones, pick up hammer stones, and fill the jungle with a steady rhythm of banging noises. Youngsters hang around with the hardworking adults, occasionally pilfering nuts and stones from them to try things out for themselves. They also get a good deal of food from their mothers, who share the kernels of cracked nuts. In this way they learn about the edibility of nuts, and with time also about the connection with stones.

  At first, infants are seen handling single objects. They play with a nut or a stone, but do nothing with them together. At the next stage, infants begin to randomly combine objects. They put nuts on anvil stones, or they push stones and nuts together. They also spend quite a bit of time hitting nuts with a hand, or stamping them hard with a foot, which of course does nothing to open them. Only after three years of futile efforts do they finally begin to coordinate multiple actions to crack a nut with a pair of stones, using one as anvil and the other as hammer. They still need a great deal more coordination and refinement, and so it is only when they are six or seven years old that their skills begin to approach those of adults.161

  What does this tell us? Here we have young apes whose actions gradually begin to resemble those of their parents without ever having been rewarded. Since they fail continuously for at least three years on end, the incentive for their imitation cannot be in its payoffs. They may even experience negative consequences, such as smashed fingers, or the frustration of knowing that there's food inside the nut while not being able to get to it. What keeps them going?

  This question comes up because it has been suggested that imitation never exists for its own sake, but is invariably strengthened or weakened by what it delivers. Bennett Galef, one of the experimental psychologists who, as discussed earlier, is skeptical about animal culture, described the need for reinforcement as follows: "In my view, although imitation might introduce some novel behavior into the repertoire of members of a population, through time (probably counted in days) this behavioral novelty would be maintained, modified, or extinguished depending on its effectiveness in acquiring rewards."163 This sounds logical enough, but is it consistent with the facts? The field research on nut cracking rather shows that young chimpanzees perform an unrewarded activity, copied from their elders, for over one thousand days without ever slowing down. Could it he that when it comes to cultural transmission, the traditional emphasis of learning psychologists on tangible incentives is misplaced? Perhaps the copying of others is more like a drive, that is, it reinforces itself.

  This would quite simply mean that social learning is socially motivated. A young chimpanzee, for example, feels close to mother, identifies with her, and expresses this closeness by watching all her moves and doing everything like her. Young chimpanzees are constantly in search of role models for infant care, feeding techniques, dominance displays, sexual intercourse, and so on. It is this social orientation that feeds their mimicry. Only when the apprentice cracker has achieved enough dexterity and strength to actually open a nut does food enter the picture. This doesn't mean that before this moment nut cracking was not goal-oriented: I rather look at it as a shifting of goals. At first, there is the orientation to the mother, and the desire to act like her. In the process, almost by accident, the second goal-to feed on tasty kernels-emerges and gradually takes over from the first.

  The same may be true of monkey imitation. Michael Huffman, an American who has worked for twenty years on Arashiyama, a mountain overlooking Kyoto, reports the curious habit of Japanese macaques of rubbing stones together. The monkeys often come down from the mountain to a flat, open area where they receive food from park wardens and tourists. Daily, one sees them collect handfuls of pebbles or small rocks. They carry these to a quiet spot, where they rub or strike them together or spread them out in front of them, scattering them, gathering them up again, and so on. When I first saw this, it looked as if they were trying to make fire, but this is of course again the human goal-seeking mind at work. Young monkeys learn this totally useless activity from peers, siblings, and their mothers, resulting in a widespread tradition within this particular troop. As Huffman notes, "It is likely that the infant is first exposed in utero to the `click-clacking' sounds of stones as it mother plays, and then exposed visually to stone handling as one of the first activities it sees after birth, when its eyes begin to focus on objects around it."164

  Exactly how the monkeys learn from each other remains a question, but it is obvious that young monkeys copy the stone handling without any reward other than perhaps the noise associated with it. Nevertheless, there are no signs of diminished enthusiasm; for decades, the activity has consistently been passed on to each and every infant born in the troop. If there is any case in the primate literature that refutes Galef's assumption that imitation requires rewards, it is this curious behavior of the monkeys on Arashiyama.

  Let me therefore propose an alternative view, which is that primate social learning stems from conformism-an urge to belong and fit in. To give this process a name and emphasize that it favors certain social models, such as mothers and peers, I will use the acronym BIOL, which stands for Bondingand Identification-based Observational Learning. Instead of being dependent on tangible benefits, such as food, BIOL is a form of learning born out of the desire to be like others. Certain social models are copied in an often playful, imperfect, and exploratory fashion. Whether or not this translates into rewards is secondary.

  For this reason, BIOL is sometimes more style than substance. A good example is the N-family of rhesus monkeys that I studied at the Wisconsin Primate Center. This matriline was headed by the matriarch, Nose, all of whose offspring had been given names starting with the same letter, such as Nuts, Noodle, Napkin, Nina, and so on. Nose had developed the habit of drinking from a water basin by dipping her entire underarm into it, then licking her hand and the hair on her arm. It was amusing to see how her offspring, and later her grandchildren, followed the same technique. No other monkeys in the troop, or any other rhesus troop that I knew, drank like this. Unless one wants to propose a gene for drinking stylewhich would be a stretch-the tradition must have been transmitted through observation. And again, rewards played no role, since the N-family did not obtain anything that other monkeys were unable to obtain.

  The self-reinforcing quality of BIOL has been overlooked. We are such law-of-effect creatures that we have trouble looking at imitation from a purely socioemotional perspective. We see purpose everywhere, and if we don't see it we feel there must be something wrong. But even if imitation is mainly socially driven, aimed at emulating favored models, the end result remains that habits and techniques spread through a population. It is at this level that the payoffs occur. The individual does not need to realize this, such as when a monkey learns to fear snakes without ever having been bitten or when a playing chimpanzee begins to combine stones with nuts. Or think about the song learning of birds: no one has ever suggested immediate rewards for their imitation. Insofar as conformist tendencies contribute to survival, they will be selected for. Indeed, the argument has been made that the desire to act like others and the ability to copy others evolved in tandem, allowing individuals to take full advantage of the knowledge and adaptive habits around them.165

  The Tortoise and the Hare

  When we loo
k back at the three earlier requirements for imitation-identification with the model, understanding of its goals, and presence of basic pre-knowledge-it is evident that the first and last are common in primate societies, underlying much of the observed imitation. But whether there is much understanding of the model's goals remains questionable. The imitation of monkeys and apes may be less goal-oriented than what we humans achieve at our best moments. This is not to say, however, that most of our imitation-a boy walking like his father, a teenager talking like her friends-isn't exactly as socioemotional as the BIOL of other primates.

  The critical question now is whether such a deficit- if that is what it is-in the imitative capacities of monkeys and apes is reason enough to ban them from the cultural domain. This is a favorite argument of some skeptics, the most extreme position being that of psychologist David Premack, who, together with his wife, Ann, claims that imitation is a spontaneous activity of the human child but not of the chimpanzee. The Premacks go so far as to say that "in non-human primates, imitation plays no role in the transmission of information, whereas in humans it plays a major role."166

  Curiously, in the same article they contradict this statement right away by discussing striking anecdotes of their own chimpanzee, Sarah, who apparently is a great imitator. Following a logic similar to Tomasello's concept of enculturation, they ascribe Sarah's brilliance to the human environment, saying that "field observations are poor forecasters of the potential behavioral complexity of the chimpanzee." Hence the idea is that human-reared apes operate on a different mental plane than wild ones, having benefited from human cultural stimulation.167

  The challenge for those defending this position is to explain why apes, and not other animals that are extensively exposed to people, such as dogs, can be pushed to such great heights. What makes apes so exquisitely educable? Any sensible theory will, in my opinion, propose that they are sensitive to human enculturation precisely because cultural influences abound in their natural environment. They are educable because they need to be. If so, the enculturation idea supports rather than contradicts the possibility of ape culture.

  Also, it is not as if Sarah is the first ape for whom imitation has been reported. Why would these observations, made up close in the laboratory, be more relevant than similar stories of imitation by apes under natural or naturalistic conditions? I am unconvinced that what an anonymous youngster does at Bossou, playing with stones and nuts until he can do what the adults around him are doing, is any less impressive than Sarah's laying a banana peel like a hat on top of a portrait after having seen a person wearing a hat. Both apes try to re-create what they have seen.

  The Premacks go on to remark that chimpanzees have been studied in the field for perhaps a hundred years but that nothing important has ever changed in their behavior. This lack of change is seen as an argument against chimpanzee culture. But couldn't exactly the same argument be used against human culture? Conservation and inertia are as much part of culture as innovation. Until recently, some peoples still lived in the Stone Age, and humanity's prehistoric record shows periods of hundreds of thousands of years without any appreciable change in tool manifacture. Chimpanzees, in contrast, have been carefully studied in the field only for about forty years.

  Speed is never what defines a process: the hare and the tortoise both get from A to B. Even if it were to take chimpanzees a million years to develop and transmit the habit of waving flags when the moon is full, I would still categorize this behavior as a cultural tradition. Here is what a classical anthropological text, by Alfred Kroeber, says about the speed of change:

  One of the most widely held preconceptions is that culture is progressive. "The progress of civilization" is a familiar phrase-almost a trite one. Simple or primitive peoples are labeled "unprogressive." The implied picture is a of a continuous moving forward and onward.

  Actually, the idea of progress is itself a cultural phenomenon of some interest. Strange as it may seem to us, most of humanity during most of its history was not imbued at all with the idea. An essentially static world, a nearly static mankind, were most likely to be taken for granted. If there was any notion of alteration, a deterioration from the golden age of the beginnings was as frequently believed in as an advance.168

  Solid Ground

  In 1999, Stephen Jay Gould commented in the New York Times that humanity has an unfortunate tendency to erect "golden barriers" that set us apart from the rest of the animal kingdom. He was reacting to reports in Nature about cultural primatology.169 Golden barriers are bound to be rejected, argued Gould, using the reports as proof of such rejection with respect to humanity's purported cultural uniqueness. Within days there were letters by distressed readers in the Times about how what apes do is "instinctive," whereas what humans do is "conscious," and how only humans possess a free will.

  In the minds of many people, culture is associated with freedom. They believe with Ashley Montagu that "man has no instincts."170 But doesn't culture restrict our freedom as much (or as little) as biology? And where do our cultural capacities come from? Don't they spring from the same source as the socalled instincts? How could one possibly, with learning and cognition so conspicuous in the lives of chimpanzees, call everything they do instinctive? Whereas we can fully expect that definitions of culture will keep changing so as to keep the apes out, the proposals heard thus far seem insufficient to do so.171 Culture requires imitation and teaching? It needs to be fast? Apart from the already mentioned problem that mechanisms are poor criteria, the question becomes again how human culture would fare. The following items would probably not be considered cultural if we were to follow the definition of experimental psychologists, which center on imitative problem solving:

  • Clothing, ornamentation, taste in colors

  • Religion

  • Cuisine and food preferences

  • Music, art, and dance

  • Social styles, such as egalitarian versus hierarchical, or polite versus rude societies

  None of these items has much to do with problem solving. If this is the touchstone, neither the Spanish flamenco nor the Scottish kilt nor Chinese food would be cultural. Needless to say, this is not how we usually employ the term. Owing to my wife's and my disparate backgrounds, I know subtle yet pervasive cultural differences firsthand. Even after decades together, we still don't agree on the right time for dinner, we have different tastes in color, and we disagree about what to discuss in public, and how. Cultural imprinting often takes place through sheer exposure and force of habit. If you bow all your life for parents, teachers, and other higher-ups, how can you ever get used to a culture where people stand upright, shake hands, and call each other by their first names? This is culture at work in our daily lives: a broad set of influences on customs, habits, tastes, attitudes, and sensitivities.

  I therefore much prefer Imanishi's definition of culture as nongenetic behavioral transmission. With this definition, we can include both the entire rich tapestry of human culture and behavior transmitted by other animals in ways that overlap with but are not necessarily identical to ours.

  Remarkably, despite his reflection in the epigraph to this chapter, and after having produced the most comprehensive review of anthropological definitions of culture, Alfred Kroeber didn't rule out animal culture as a possibility. He didn't necessarily cling to the human standards of language, values, and full-blown imitation as part of culture. Hearing of the "dance" of Kohler's chimpanzees, Kroeber speculated that if an ape developed a new dance step, or a new posture, and if these acts were then picked up by others, became standardized, and survived beyond the inventor's generation, "we could legitimately feel that we were on solid ground of an ape culture." 172

  By accepting a broad, inclusive definition we can make the necessary connection between human and animal culture without in any way devaluing the former's achievements. The fact that primates sometimes duplicate behavior, such as the rubbing together of stones or a special drinking technique, that con
fers zero advantages is extremely telling. It teaches that cultural learning is not about rewards, but about fitting in. Identification with others and a desire to conform are tendencies we easily recognize in ourselves, as reflected in concepts such as "peer pressure" and "role model." We can now assume these tendencies, which underlie all forms of cultural transmission, to be far older than our own tenure on this planet.

  "Certain kinds of information can only be transmitted by behavioral means. If the transmission of this kind of information is adaptive, then there would be strong selection pressure for culture."

  John Bonner, 1980

  "Chimpanzees would not greatly miss their so-called tools. They would find other things to eat, get by without medicines, not perish for want of leaf-sponges."

  Barry Allen, 1997

  cracking is such a noisy business that a French colonist, in Ivory Coast, once speculated that an unknown jungle tribe must be forging iron. A Portuguese Jesuit in Sierra Leone got closer to the truth, writing, in the early 1600s, that he had heard how chimpanzees collected handfuls of paten nuts in the forest to break them open with a stone.' Obviously, this would have been hard to do with a single stone. We had to wait until 1951 for the first eyewitness account, published as a half-page note in a scientific journal by Harry Beatty, an American expatriate to Liberia, who probably had no idea of the momentous importance of his discovery:

  At last, I arrived at the edge of the dark, matted vegetation and glanced along the path before me. It was deserted, but I noticed a shell heap twenty-five feet away.... A moment later an adult male chimp came ambling around a bend, bearing an armful of dried palm nuts, supporting himself on his right knuckles. He reached the rock, sat down clumsily and proceeded to select a nut. He then picked tip a chunk of rock and pounded the nut which had been placed on the flat surfaced rock. I watched this procedure for several minutes until an alarm note from the rear sent the troop scurrying off.'"