Becoming a Tiger: The Education of an Animal Child

by Susan McCarthy

  The eight infant chimpanzees played on the walkways, played with branches that fell off the trees and that were brought in so they could make nests, and were observed from the comfort of the booth. One of their games was to stand branches on end and swarm up as quickly as possible before they toppled over. A few years went by. One day six-year-old Rock, balancing on a pole near the observation booth, started to topple, stuck out his foot, and steadied himself. Aha! He could look into the booth! He could slap the glass! A week later Rock invented the ladder. The scientists arrived in the morning to find the observation booth a shambles. Rock had discovered that if you propped the branch against the wall under the booth, you could climb up, get in the observation booth, trash the booth, and escape. As reconstructed, in the night Rock may have been balancing on a pole next to the booth, toppled toward the wall, steadied himself there, and realized that he could now reach the booth. Rock’s best friends promptly took up the same exciting activity, escaping with great frequency. Usually they returned of their own accord, but sometimes they had to be captured, often with lavish bribes of fruit. Since it was impossible to keep the apes out, the observation booth was boarded up.

  The chimpanzees now propped branches on the walkways between the trees, to the portions of the trunks above the electrified wiring. (This required careful placement on the narrow planks of the walkways.) This allowed them to climb into the crowns of the trees, which they destroyed. Rock got hurt falling off a dead branch, and one of the trees toppled onto a walkway, so the dead trees were cut down, leaving only stumps, some of the posts of the walkway system, and a few planks. The industrious apes uprooted posts and stumps and wrenched loose the planks, and used them to escape. Posts, stumps, and planks were confiscated. Then they jammed short sticks into the cracks between sections of the fence to use as pitons, and escaped. Finally the entire colony was shipped to a monkey island in another state.

  Stone tools? My folks used to make stone tools

  A project to see if the bonobo Kanzi could learn to make stone tools like the ones made by prehistoric hominids proceeded in unexpected ways. The object was for Kanzi to flake flint into sharp-edged cutting tools. He needed to strike a piece of flint at the right spot with another rock. If he succeeded, he could use a sharp flake to cut a rope tied around a box containing some fabulous food item. Kanzi understood about the food, and he understood about cutting the rope, and, having watched demonstrations, he understood about hitting one rock with another to make a flake. But he had a hard time making flakes that were big enough, and after a few months of trying he was getting quite frustrated. One day he tried to get his friend, primatologist Sue Savage-Rumbaugh, to do it for him, but she wouldn’t. He sat and thought, with rock in hand, and suddenly rose to his feet and dashed the rock to the ground with all his might. It shattered, and Kanzi uttered a glad cry, snatched up a nice big flake, and headed for the box. Since early humans probably did not flake flint this way, the researchers were disgruntled by Kanzi’s method, and they carpeted the floor to thwart him. Kanzi tried hurling a rock at the floor, but nothing flaked off when it hit the cushioned surface. Undaunted, the brilliant bonobo examined the carpet till he found a join, peeled it back, and smashed the rock on the hard floor beneath. “We have assembled a videotape of the tool-making project, which I show to scientific and more general audiences. Whenever the tape reaches this incident there is always a tremendous roar of approval as Kanzi—the hero—outwits the humans yet again,” writes Savage-Rumbaugh.

  Capuchins and tools

  Those who work with octopuses grumble about the hegemony of vertebrates; those who work with birds grumble about the hegemony of mammals; those who work with marsupials grumble about the hegemony of placental mammals; those who work with buffalo grumble about the hegemony of primates; those who work with monkeys grumble about the hegemony of apes; those who work with gibbons grumble about the hegemony of the great apes; those who work with orangutans grumble about the hegemony of the African great apes. And those who work with New World monkeys grumble about the hegemony of Old World monkeys and apes.*

  Therefore all those who would strike a blow against hegemony† will be glad to hear that tufted capuchins, who are New World monkeys, have been spotted using tools to crack nuts, just like chimpanzees. Researchers Eduardo Ottoni and Massimo Mannu watched a group of tufted capuchins living in the Ecological Park of the Tietê River in Brazil. These are free-ranging former captives who had been living in the park for about seven years. This particular group was founded by capuchins who had been put on islands in the river but had swum to the mainland.

  Capuchins had been reported cracking palm nuts by banging the nut against a tree or by smashing two nuts together, but residents in areas near where capuchins live also claimed that they used stone tools, and suggestive piles of stones and nutshells had been detected. Sure enough, these capuchins cracked palm nuts with a hammer stone and anvil stone. Sometimes the anvil was not a stone but a root or an old piece of pavement (not all parks are in pristine forest), and one hammer was a piece of wood. Capuchins aren’t big monkeys and they usually held the hammer stone in both hands as they brought it down. Unlike chimps, capuchins can steady themselves with their tails as they perform this feat. Sometimes the monkey leapt clear off the ground with the effort.

  Fifteen out of the 18 capuchins cracked nuts, and the 3 who didn’t were infants. The most frequent nut crackers, by far, were the juvenile monkeys. Perhaps this is because they like fiddling with stuff, and perhaps it is because the adults chase them away from easier food sources.

  Ottoni and Mannu classified some nut cracking as inept, such as when the monkey missed the nut entirely or didn’t even put a nut on the anvil. Infants were by far the most inept, then juveniles, then subadults, then adults. They predict that it takes a capuchin years to become efficient.

  Before you give a capuchin the Nobel Prize

  But it so happens that capuchins absolutely love to pound on things. Many years ago the psychologist Elisabetta Visalberghi was passing the capuchins in the Rome Zoo and saw an adult male pounding on an unshelled peanut—with a boiled potato. “The fact that capuchins were doing something smart in a silly way, or something silly in a smart way, struck my interest,” writes Visalberghi, who has since studied capuchins extensively.

  Young capuchins love to pound, so if one capuchin is pounding on a nut and another one starts pounding things, it’s not necessarily imitation. It could just be stimulus enhancement. It’s pounding time! They seem to be enthusiastic manipulators of objects and terrible imitators. Of her capuchin Andy, Kathleen Gibson writes, “His skills in this regard are so poor that he has never even imitated my action of unfastening his leash.” This although he is a clever fellow who rakes things into his cage, picks pockets, and wraps himself in a towel when watching scary war movies on television.

  In another publication, Visalberghi and Luca Limongelli write, “During our 17 years of research experience with cebus [capuchin] monkeys…we have alternated between marvelling at their cognitive accomplishments and being plunged to the depths of despair over their inability or extraordinary reluctance to learn a variety of apparently simple tasks.”

  Captive capuchins were presented with a large box containing maple-flavored syrup. The box had holes in the top which led into plastic pipes which led down to the syrup. When they first saw the box, there were wooden dowels in the holes, and several of the capuchins pulled the dowels out and licked the syrup off, then reinserted the dowels to get more syrup. Later they were given the same box, but no dowels. The researchers had put sumac branches in the cage. The monkeys tried to get syrup by dipping in monkey biscuits, but that didn’t work. On the second day the capuchin Nick bent a twig from a nearby branch into one of the holes, without actually removing the twig, and licked syrup off the end. Immediately Fanny, who had been watching Nick, removed a stick from a branch and dipped for syrup. The next day both Nick and Fanny broke off sticks to dip for syrup. Nick further cov
ered himself in glory by snapping off a side branch of a stick he had broken off, “modifying an already-constructed tool by subtraction.”

  There were several baby monkeys in this colony, and they wanted syrup too. Alice’s daughter Quincy, eight months old, explored the box extensively. She stuck her fingers in the holes. If monkeys would let her, she’d remove sticks they had inserted. Grasping dimly that sticks had something to do with getting syrup out of the box, Quincy took small twigs in her hand and slapped them against the side of the box. After 17 days, Alice and Quincy dipped a stick together. “Quincy’s hand was literally on her mother’s as the stick was inserted.” Quincy got to pull the stick out herself and lick the syrup off. Within two days she was trying to do it herself, ineptly, holding a stick in two hands and stabbing it toward the box, missing every time. Two days later she succeeded in dipping a stick and two weeks later she was making her own sticks.

  This was before the free-ranging capuchins in Brazil had been spotted cracking nuts, and the researchers puzzled over the fact that capuchins hadn’t been seen to use tools in the wild. (The following year, a wild white-faced capuchin was sighted beating a poisonous snake to death with a branch. The author of the report added that capuchins often throw things at coatimundis, tayras, opossums, spider monkeys, and the author. On one occasion a capuchin who ran out of branches to throw at the author threw a squirrel monkey at her. I say it’s tool use.)

  Cause? Effect? Your point?

  In experiments with capuchins trying to get food out of a clear plastic tube, Visalberghi and colleagues clarified what capuchins did and did not understand about tool use. The original apparatus was a clear plastic tube, mounted horizontally. In the middle of the tube was a peanut. To get the peanut out, the monkeys had to push it out by inserting a stick in one side or the other. They tried all kinds of methods, some of them fairly witless, but eventually succeeded. Visalberghi and Limongelli set up a variation in which the tube had a small (clear) trap on one side. If the capuchin pushed the peanut through from one side, the peanut would come out. If it pushed from the other side, the peanut would fall into the trap. Argh! If the peanut fell in the trap the capuchins bit the trap and shook it fiercely, but people who work with monkeys have learned to make the apparatus sturdy. Sometimes they watched the progress of the peanut as they pushed it, and held a hand under the tube, moving it as the peanut moved “as if by doing so they could prevent its fall” into the trap. That doesn’t work either. They got nervous as the peanut approached the trap. But three out of four never improved, never showed any sign that they understood why the peanut might fall into the trap, only that it might. The fourth capuchin, a juvenile, did show improvement. Less and less often did she shove the peanut into the trap.

  Alas, the successful capuchin, Rb, still didn’t understand what she was doing. She had hit upon a strategy which is summed up as “insert the stick into the opening of the tube farthest from the reward,” but didn’t know why it worked. If they turned the tube so that the trap was on top, and there was no risk of the peanut falling in the trap, she was just as anxious, and peered into the tube just as many times to make sure she was using the end farthest from the reward.

  Bowling for apples

  Researchers who gave Japanese macaques a tube-and-stick problem got a different response. They fixed a large acrylic tube to a log at a site where they left food out to attract monkeys. To teach the monkeys to use a stick to get an apple out of the tube, they began by putting an apple in the middle of the tube, where the macaques could see it but couldn’t reach it, with a hooked stick in the tube touching the apple. After various changes in the procedure, some monkeys could pull an apple out with a hooked stick, some could search for sticks to pull or push the apple out, and Tokei invented the idea of throwing rocks into the tube to knock the apple out.

  Tokei had another method for getting apples: child labor. Babies under six months old were small enough to get in the tube. While the mothers Togura and Tomato would pull their babies out if they had gone in the tube, and take the apple from them, Tokei was more proactive. She’d take her baby and stuff it in the tube.

  Birds with sticks

  In Queensland, Australia, there’s a species of palm cockatoo which makes even more hullabaloo than most cockatoos. They perch in tall trees and yell their heads off, and back this by stamping on tree trunks with their feet. If that isn’t loud enough, they pound on trunks with nuts or sticks, striking up to 100 blows. Palm cockatoos have been seen snapping off branches and trimming them into drumsticks of their preferred size and shape. (Birdwatchers have been seen sneaking around and gathering discarded drumsticks.) A male palm cockatoo will perch atop a snag, stretch his wings wide, and pirouette while drumming on the tree with the drumstick held in one foot. Female palm cockatoos are thought to like this very much. One pair of palm cockatoos were both seen drumming on the day before their baby left the nest for the first time.

  Otter not

  Otters are skilled manipulators. The impulses that lead them to feel among the stones in a river or tide pool in search of lurking edibles such as crawfish or shrimp lead captive otters to juggle hazelnuts or slip their paws into pockets and fish out keys. Since we too like to manipulate things with our hands, this looks smarter to us than if they were doing it with, say, their lips.

  Susie, a captive Alaskan sea otter, was given stones so she could display the famous propensity of sea otters to crack open clams. Susie also used them to pound on the edges of her concrete pool and smash the bolt holding the cover on the pool drain, which she presumably wished to investigate. They took the stones away.

  Thumbs? I don’t even need hands

  A group of dolphins in Shark Bay, in western Australia, apparently use sponges as tools, but no one knows how. At first observers thought they were seeing a dolphin with a hideous growth on her face, but closer inspection showed that several female dolphins were in the habit of putting cone-shaped sponges on their snouts. Whatever they are doing with sponges on their faces, they do it underwater. When they dive after appearing at the surface with a sponge, the curve of the dive indicates a deep dive. They sometimes reuse a sponge, but they also get new sponges. The dolphins are occasionally seen to surface chewing something, and the amount of time they spend in this pursuit suggests they are using the sponges to forage in some way. The leading guesses at this point are that the dolphins use the sponges to protect their faces either from the spines or stingers of prey like lionfish or from abrasion by coral grit as they search for prey in the seafloor sand. Wild dolphins also smack yellowtail bream they’ve caught against the ocean floor to snap the heads off. (By many definitions this doesn’t count as tool use, but it is a useful trick if you don’t like eating bream heads.)

  Captive bottlenose dolphins Frankie and Floyd tried to chase a moray eel out of a crevice. The eel wouldn’t go. One of the dolphins killed a scorpionfish and held it by the stomach to avoid its poisonous dorsal spines. Then he prodded the beleaguered eel with the scorpionfish. The dolphins also liked to play with pelican feathers, positioning them over water jets and then chasing them. When feathers were scarce, the dolphins would swim up to pelicans and yank feathers out.*

  The cheaper baby buggy

  Gold-cheeked flag cichlids are attentive parents. A couple guard, clean, and fan their eggs, and when the fry hatch out they take them into their mouths and transport them to the places the parents feel the babies ought to be. The eggs are typically laid on a leaf, and the parents busily shuttle the leaf from one spot to another. In laboratory tests, they choose light small leaves that are more easily dragged in preference to large leaves to which some troublemaker has secretly glued small lead weights. A pair will move the leaf/baby buggy to deeper water with better cover if that is an option, and they move it more if there is a predator around, or even a minnow-shaped fishing lure painted to resemble a predatory pike cichlid. Also, if they see people approaching the tank, they drag the leaf to the back of the tank, usually be
hind a plastic plant or other object.

  What have you done to your nose?

  Kipling’s fictional Elephant’s Child uses his new trunk to break off a branch for a fly-whisk. Researchers observing Asian elephants in India often saw them switching flies with branches they had broken off. But since the elephants broke the branches off trees they were in the process of dining on, and since the elephants often ate the branches after switching them at flies, it could be argued that the elephants were not breaking branches for the purpose of switching flies, but just for eating. It would be as if you were eating celery, were bothered by a fly, waved your celery at the fly, and then ate the celery. Do not expect big tool-use kudos for that.

  The researchers focused on semicaptive elephants at a logging camp and a riding camp. Finding the elephants in camp, with flies about, the researchers presented them with enormous branches of Butea trees. Butea leaves don’t taste good, so the branches were useless for eating. They were also too big for switching flies. Often the elephants picked the branches up, broke them to a useful size, and switched flies on their sides, backs, and bellies. They either put one foot on the branch and pulled a smaller piece off with their trunk, or they coiled their trunk around the branch and twisted a piece off.