There were disputes, since people and lions stole kills from each other, but they did so in a quiet, look-we-outnumber-you-do-the-math kind of way, not with hostility. “I thought we were finding out about lion nature,” Thomas wrote.
Lions and people had then lived together in the Kalahari for a long time. In the 1960s the government evicted the Ju/wasi from the part of the Kalahari that became Etosha National Park. In the 1980s, Thomas revisited the area, and found that the lions had changed. Her first hint of this was when two teenaged lions charged and chased the van in which she was driving. Thirty years without human inhabitants had broken a chain of cultural transmission. Young lions had grown up without ever seeing their elders respond to humans. They did not use the dance of the oblique departure. Humans (other than park rangers in jeeps wielding guns with anesthetic darts) were a novel phenomenon crying out to be investigated. Do they scare easily? How fast can they move? And perhaps even—are they tasty? Deprived of the observational learning experiences they would have had if they had met people while with the elders of the pride, they were ready to learn by experiment.
Anubis versus hamadryas
The closely related hamadryas and anubis baboons have very different male-female relationships. Female and male anubis do not have enduring relationships other than friendship. Mating takes place when the female is in estrus. Male hamadryas, however, control one or more females in an arrangement Hans Kummer calls a marriage. The male herds the females together, keeps an eye on them, and is deeply domineering. He does this at all times, not just when the females are in estrus (which isn’t often). Kummer and colleagues performed the experiment with wild baboons of putting hamadryas females in anubis troops and anubis females in hamadryas troops. When an anubis female was placed near a hamadryas troop, a male hamadryas immediately claimed her, and was then vexed by her reluctance to follow him. Communication was not the problem: she had no difficulty understanding what he wanted, but she found his wishes bizarre. He attacked her every time she strayed, more harshly each time. Within half an hour, an anubis female knew that when the male stared at her, she was too far away and was supposed to come closer. But even knowing that, she didn’t like it, and as the days went by and the male had to keep rounding up his exotic wife, he gave up. “The experiment had shown that hamadryas males can enforce a marital relationship with threats but cannot maintain it permanently,” Kummer wrote.
Meanwhile a hamadryas female placed in an anubis troop would attach herself to a male and groom him devotedly. Soon she would notice that he made no efforts to herd her, and that he did not protect her from other baboons, and she would lose interest in him. One hamadryas female found a nice male anubis who did protect her, and although he did not herd her, he followed her around. “Not a bad choice, it would seem,” wrote Kummer. “But she finally left this male too and lived unmarried.”
Landmarks, paths, and migration routes
Since the natural landscape changes over time, a lot of important information about where to go and how to know when you’re on the right track to get there cannot be entrusted to the genes. Cultural transmission is a great way to pass on this vital data in many species.
Teenaged French grunts spend their days schooling with other juveniles in favored spots on the coral reef. At twilight the juvenile fish swim together along “featureless (to human observers)” routes to feed in sea grasses, and at dawn they migrate back to their usual coral head. The routes can be more than half a mile long. Because grunt generations overlap, it seemed possible that they were learning the routes from each other, not simply taking the route that would be obvious to any French grunt. Curious naturalists kidnapped juvenile grunts and added them to schools in other parts of the reef. When twilight came, the new kids followed the locals to the sea grass beds, and at dawn they went back with them. When the scientists went one step further and removed the locals, the new kids kept taking the route the locals had shown them. French grunts who were slapped down in a new area from which the residents had been removed, and who didn’t have anybody to follow, worked out routes for themselves. But the routes they chose were different from the ones the previous residents had laid down.
Buffalo shuffle
Along the shores of Lake Manyara, in Tanzania, buffalo herds rest in the late afternoon. The buffalo lie down, some on their sides, and there is little activity. Most buffalo do not even chew their cuds, the bulls leave the cows alone, and the calves do not pester their mothers. “It seems that nothing is happening,” writes researcher Herbert Prins. “However, this is not the case.”
After Prins had been studying buffalo for two years, he realized that what he had thought was a random activity of no importance—a cow getting up, shuffling around, and then lying down again—was actually meaningful. He had thought they were just stretching their legs, but one day it occurred to him that the cows who did this adopted a particular stance, held their heads higher than usual, but not so high as to indicate alarm, and gazed in one direction for about a minute. Each time a cow got up, she’d gaze in the same direction, and this direction indicated where the herd would go when they ended their rest period. In a herd of 950 buffalo, normally about 5 cows might be standing and gazing at any one time. Prins calls this the “voting posture.”
Around six o’clock, or when the shadow of the escarpment moves over them, the herd begins scrambling to their feet. Calves get up and nudge their mothers to do the same. Within a few minutes, Prins reports, “they start trekking, at the beginning independently of each other, in the same direction.” Such herds do not seem to have leaders, and an animal that is in front at one moment will not be there for long. Often bulls may be seen at the front of the herd, but if they stop and graze, the cows walk on past them, and the bulls follow.
The herd heads to an area where they will graze by night and the following morning. Once Prins had figured out what the staring cows signified, he experimented with trying to head the herd off with his car, chasing them away, or splitting the herd, but in every case, the buffalo went around, doubled back, or regrouped, and went where they had planned to go all along.
Sometimes the herd does not achieve consensus in the direction of their voting postures, and then they may split into two herds.* “Voting” is done by adult cows, with a very few teenagers (subadults) of both sexes taking part. Bulls, who are transient members of the herds, do not vote, and when they get up during the rest period, the direction in which they look, walk, or face while grazing is random.
Prins argues that these buffalo live in an area of fine-grained patches, where at any given time the grazing is too low in protein in many spots (less than 7 percent). They compete for grazing with other herbivores, particularly elephants. The decisions about where to graze are important to their survival and are based on local knowledge of the state of the grazing in many locations. (So when I said earlier that eating grass probably didn’t require as much learning as eating grass-eaters did, that was too glib.)
Going nowhere
Many species of migratory creatures also have sedentary populations. This isn’t genetic, as it is possible to indoctrinate a bird from a migratory population into stay-at-home ways. Whooping cranes follow their parents in migration and learn the route. But if their parents do not migrate, neither do they. Conservationists have been able to establish a nonmigratory population of cranes in Florida, the children of captive cranes.
Young greylag geese at a research station in the Alm Valley of Austria, where the water does not all freeze over in winter, show the migratory urge on stormy days in fall. Having been raised by humans or by other geese who are not accustomed to migrating, they have no place to go. They fly for hours, in classic V formations. In the evening they land, back at home.
It’s a bird, and a plane, and a guy in a plane in a bird suit
In addition to the sedentary population of whooping cranes, the International Crane Foundation (ICF) is also trying to establish a new migratory population with a diff
erent route. Instead of migrating between Canada and Texas, these cranes will migrate from Necedah National Wildlife Refuge in Wisconsin to Chassahowitzka National Wildlife Refuge in Florida. There are no adult cranes who know the way, so instead the ICF is leading cranes on the first flights in ultralight planes. To avoid imprinting, the people around the young cranes feed them with realistic whooping crane hand puppets and wear whooping crane outfits (and never speak), so the pilots must also wear crane suits. Enormous, implausible crane suits, but it seems to be working.
Leading cranes in an ultralight is dangerous work, especially when predators appear, and worried young birds scramble to fly next to their parental figure, the plane.
The young cranes were first taught to follow the planes on local flights. Then the pilots led them south in easy stages of 20 miles a day. Often bad weather grounded them. Cranes led by real bird parents can soar on thermals and save energy, whereas cranes flapping behind a slow plane work much harder. In the first group, the Class of 2001, one crane dropped out over Kentucky. A search was launched for the missing bird, Number 6. When he fell behind, Number 6 returned to the place where they had spent the previous night, an airstrip in Adair County. A resident looked out her window, saw lonesome Number 6, and alerted the search team. By the time they got there, he was gone. Fortunately he had not gone far, so they were able to get radio signals from a transmitter he was wearing. They followed the signal to a river valley and, figuring he might be near the river, began broadcasting crane calls. The young bird answered and appeared flying above them. Desperately hoping to call him down to a suitable landing spot, team member Dan Sprague, clad in his crane suit, sprinted to a clearing at the top of a hill, blasting crane calls on his crane vocalizer. No sooner had he reached the clearing than Number 6 landed beside him, peeping pathetically.
The cranes made it to Florida, and the following spring they flew back to Wisconsin by themselves, with no one leading them. They remembered the way and made excellent time. The Classes of 2002 and 2003 also did well. The ultimate test is whether the birds will breed. If they do, they should lead their children on the new route that the airplanes showed them.
The mountains are up, you fools
Reindeer and caribou migrate yearly, using traditional routes, although, in the case of caribou, not always the same routes each year. Reindeer do not like to travel alone or in small groups, and prefer the safety of the largest possible herd, but they also like to be with reindeer they know and to migrate together with them. Although their urge to migrate is innate and they may have an innate compass that tells direction, maps are not innate. Young reindeer who travel with the herd may learn landmarks along the way, thus acquiring a map. In the 1960s, some Swedish reindeer farmers, worried that grazing conditions along the migration route wouldn’t support all the reindeer, decided to lend a hand. In the autumn, they rounded up reindeer, loaded them into trucks, and drove them to the traditional wintering grounds. So far so good.
But in the spring, when the reindeer migrate back to the mountains, many stayed behind on the winter range. “This has caused much trouble to the reindeer owners,” zoologist Yngve Espmark reported. The problem may have been partly that many animals did not know the route and partly that their social structure had been disrupted when they were put on trucks. Forced to scatter on the winter grounds in order to get enough to eat, they may not have known the landmarks or anybody they felt safe about following in the spring migration, so they stayed put.
The big chimpanzee survey
The strongest case for animal culture comes from a survey of wild chimpanzee groups across Africa. Comparing chimpanzees in Guinea, Ivory Coast, Uganda, and three locations in Tanzania, the sites of the seven longest-running studies, researchers counted 39 behaviors that took place in some sites and not others or that were done in different ways. They looked at the impressive stuff, like nut cracking, and at less serious stuff, like the custom of using large leaves as a seat cushion or using a leafy branch to fan away flies or doing rain dances. “The profiles of each community…are distinctively different, each with a pattern comprising many behavioural variants,” the study’s nine authors write.
The Sassandra River, enemy to knowledge
A dramatic example of differing cultures comes from West Africa, where there are chimpanzees living on both sides of the Sassandra River. There are coula (Coula edulis) nuts on both sides of the Sassandra. And there are stones on both sides of the Sassandra. Yet the chimpanzees on the west side of the river crack coula nuts between stones and the chimpanzees on the east side apparently do not. The reason may be historical and cultural. About 17,000 years ago serious drought conditions allowed a tongue of the desert to reach the sea from the north, cutting the West African forest lands in two. During this period, it is guessed, the chimpanzees in the western forests learned to crack coula nuts. When the drought ended, the forests returned and the river swelled. So there was forest on each side of the river, but chimpanzees could not cross. Further north the tropical forest changes to semideciduous forest, poor in nut trees, and so although chimpanzees can cross the river there, the nut-cracking culture doesn’t reach so far north. Thus it’s suspected that the culturally transmitted invention of nut cracking would come as intriguing news to the chimpanzees east of the Sassandra.
Rehabilitation and culture
An animal raised by people may have a culture, but it won’t be the same as the one its wild peers have. If the plan is to release the animal into the wild, this may create problems. The released animal may not know where to go (because it has never seen others go there), or what to eat or how to eat it. It may also (like the rehabilitated orangutans with bad manners described earlier) have a hard time fitting into the existing culture, if there is one.
It may be possible to save a species, through captive breeding, but to lose its culture when no wild individuals are able to pass what they have learned to subsequent generations. Whatever a tiger learns in an empty cage, it’s not likely to be of much use if it is released in the woods. If there are no animals left in the wild, then the young animals must invent their culture from scratch or be supplied with some of its elements—like crane migration routes—by the rehabilitators.
A tropical island
In 1987, Govindasamy Agoramoorthy and Minna Hsu released some captive chimpanzees on a swampy island off the coast of Liberia. These chimps came from a laboratory that used them for vaccine research, and some had been pets before that. (People who get baby chimpanzees as pets usually betray their darlings in one way or another once they become moody, mischievous teenagers with enormous teeth, muscles like steel bands, and minimal impulse control. It is fortunate for our species that human teenagers cannot thus be given or sold to labs.)
Before release the chimpanzees were kept in large outdoor enclosures on the island in social groups. They were released only if they were in good health, and only younger chimpanzees were selected, since the researchers had found in the past that older apes were harder to rehabilitate. Thirty were released, with the younger and lower-ranking apes being given first go at settling in, followed by the older, bossier chimps.
Once released, a few chimps preferred at first to sleep on top of or in the holding cage, but most of them made nests in trees like wild chimps, and soon all of them did this. Seven of the chimps, who had been pets most of their lives, couldn’t handle the change, partly for social reasons. There was fighting, and three chimps had to be temporarily taken away for medical treatment. The first two babies born did not survive.
Many of these chimps had shown stereotypical captive behavior before release—they rocked, pinched themselves repeatedly, or ate their own feces. After release, this stopped. Although Agoramoorthy and Hsu provided food, it proved unnecessary. Most of the chimps started gathering wild food within a few days, climbing palm trees and eating nuts, fruits, plants, and insects. The chimps immediately began using tools, employing rocks to smash nuts they placed on tree trunks. It’s unk
nown whether the chimps had seen or done anything like this in their previous lives, or whether it just seemed like the obvious thing to do with really hard-shelled nuts. I myself have reinvented this technique on camping trips when cones full of pine nuts were lying around, and I didn’t feel all that smart.* One week after his release, a male chimpanzee was seen tackling a weaver ant nest, eating ants and their eggs. (This is something that never occurs to me to do when I am camping.)
“Younger chimpanzees watched and learned feeding strategies from older animals,” Agoramoorthy and Hsu write. Though the older chimps knew more, the younger ones “learned social and survival skills more quickly than older animals.” In 1989, civil war in Liberia forced the researchers to abandon the study. In the late 1990s, there were still chimpanzees living on the island, and more babies had been born to them.
Uncultured youth
When captive-reared California condors were released, they showed a distressing tendency to hang around human habitations in gangs, vandalizing property, flying into power lines, and getting into trouble. The condor recovery team has concluded that simply raising chicks with condor puppets is not enough. Mike Wallace, of the California Fish and Wildlife Service, and head of the team, puts some of the blame on the kibbutzlike rearing system in which the young birds are raised together in large cages. While this reminds them that they are condors, not human beings, the atmosphere is one of a “big rumpus.” In nature a condor chick is an only child, whose sole companions are its parents, and the tone is more staid. “It produces a more timid, cautious bird, one more likely to survive,” Wallace told The Economist. The answer may be to release the young birds with older mentors, who will encourage serious study of life skills as opposed to hanging out in rowdy groups in parking lots daring each other to eat car parts.
Becoming a Tiger: The Education of an Animal Child Page 32