Introduction to Animal Culture
On a grassy slope above the shore of Lake Tanganyika in the east African nation of Tanzania, two male chimpanzees spot a hole in the ground, into which a long column of ants is marching. The chimps pause for a moment beneath the light drizzle of an early morning rain and then amble to the hole—the entrance to the ants' nest—for a closer inspection. The chimpanzees, lifetime residents of Tanzania's Gombe Stream National Park, expertly select several long sticks and sit down beside the nest. Slowly, each of them extends a stick into the hole and watches as some of the ants swarm up the probe. As soon as either of the chimps gauges that the lower half of the stick has become covered with ants, he extracts it from the nest. He then quickly gathers the tasty insects from the stick with his free hand and pops them into his mouth.
Across the continent in the Tai Forest of western Africa's Ivory Coast, two other male chimps have also discovered a nest of ants. They each find a suitable tool—a short stick, rather than the long probes favored by the Gombe chimps-and begin dipping it into the nest entrance to fish for a meal. After the ants guarding the nest climb up the sticks, the chimps sweep the sticks directly across their smacking lips and, without using their hands, draw the ants into their mouths.
At the same time that the chimps are enjoying their morning snacks, two other mealtime rituals are being played out by other primates (the order of mammals that includes humans, apes, and monkeys) far to the west. In St. Louis, Missouri, two human families—one whose ancestors came from Asia and the other whose forebears originated in Europe—sit down to dinner at separate tables in a Chinese restaurant. Both families order their favorite dish of spicy orange chicken. When the food is served, the Asian family begins eating its meal with chopsticks, while the other family picks up forks.
Since the dish could be eaten with either chopsticks or forks, the preference for one type of utensil over another is simply a reflection of cultural differences between the two families. There's nothing unusual about that. But what about the differences in the ways the Gombe and Tai chimpanzees perform ant fishing? Could those individual preferences also reflect differences in culture? Since all of the chimps are of the same species, it is unlikely that genetic differences could account for the variations in behavior. Thus, the different approaches to a similar task, ant fishing, are likely to be learned behaviors within the Gombe and Tai social groups. That means that knowledge may have been passed from one chimp to another. In other words, the chimps seem to be exhibiting behavior that could be called culture.
Social scientists have long maintained, however, that only humans are capable of possessing culture. Are they wrong? Do chimpanzees—and perhaps even other animals, such as monkeys, whales, and birds—also possess a form of culture? Many scientists in 2000 believed that the answer to that question is yes. But others insisted that culture is a purely human phenomenon.
What Do Scientists Mean By “culture?”
Scientists have debated whether animals have culture at least since the late 1800's, when the British physiologist and psychologist George Romanes proposed that some animals display behaviors that indicate a high degree of intelligence and an ability to learn. Other scientists, however, disagreed with this conclusion, believing that animal behavior is hard-wired in the brain. Over the years, scientists on both sides of the issue divided themselves into two camps, the culturalists and the anticulturalists. The culturalists contend that animals are a lot smarter and more adaptable than most people think. The anticulturalists argue that animals, regardless of their intelligence, are incapable of culture.
Central to this debate is defining what exactly is meant by culture. One requirement for culture that is accepted by scientists on both sides of the issue is imitation, or learning through observation. Researchers agree that cultural traditions among humans are learned through imitation. An American family in the Midwest may learn to use chopsticks from a daughter who attended school in Japan. In another example, most American teen-agers since the 1950's have learned that rock music is the cool music to listen to. Rock has become a cultural tradition for young people largely through imitation, as teens embrace the predominant musical preferences of their peers.
Individual family traditions are yet another type of cultural behavior learned through imitation. A mother follows a particular recipe for a German chocolate cake because her mother did so. A boy learns how to sail the family boat by watching his father. One thing that these traditions have in common besides imitation is that they are not genetically determined.
Like these examples from human culture, animal behaviors such as ant fishing are not clearly determined by genes and seem to spread from one individual to another through imitation. However, anticulturalists argue that the definition of culture involves more than just imitation. One of the leading voices of the anticulturalist camp, psychologist Bennett G. Galef of McMaster University in Ontario, maintains that culture must be purposefully taught by an individual with the intention of passing on knowledge to another. And teaching, he notes, is a difficult thing to prove in animals. Another factor that Galef and many other anticulturalists believe is necessary for the spread of culture is a spoken language—something that no animal possesses.
Culturalists, however, contend that making a spoken language a requirement for culture amounts to stacking the deck. No shared animal behavior, regardless of how sophisticated it is, could then qualify as culture. Many culturalists, including psychologist Andrew Whiten of the University of St. Andrews in Scotland and Jane Goodall, the renowned zoologist who has spent her adult life studying chimpanzees, think culture should be defined more broadly. They believe that the spread of a behavior through a group of animals by observation and imitation qualifies as culture. Under that definition, the transmission of an insect-fishing technique from one chimpanzee to another is indeed a form of culture.
Chimpanzee Tool Use and Social Behavior
Although other scientists had previously observed chimpanzees in captivity using tools, Goodall was the first scientist to witness chimps in the wild engaged in that activity. On an October day in 1960, soon after she arrived in the area that is now Gombe Stream National Park, Goodall noticed a rustling in the tall grass on a slope. She crouched to the ground, pulled out her binoculars, and watched as a chimpanzee dipped a grass stem into a termite nest to get at the burrowing insects. Over the next several years, Goodall made many observations of termite and ant fishing and discovered that the entire troop of chimpanzees at Gombe engaged in these behaviors.
Beginning in the 1970's, other teams of scientists began studies of chimpanzee behavior in different regions of Africa. In 1999, seven research teams, under the guidance of Whiten, pooled their data and published their findings in the British journal Nature. The investigators reported 39 different chimp activities that met their definition of culture as behavior that spreads throughout a social group through imitation. The most significant of these behaviors were the use of simple tools and activities related to grooming and courtship. Most importantly, the different groups of chimpanzees took individualized approaches to similar tasks. These variations could not be explained by either genetic or environmental differences, and so they must have spread through imitation and—possibly—intentional teaching.
For example, the scientists described the varying insect-fishing methods used by different chimp groups. They noted that the chimps at Gombe usually use a long stick or stem to extract termites and ants from their nests, and they tend to remove the insects from the probe by swiping their hands along it. Chimps at Tai and at a site called Bossou, in Guinea, are more likely to fish with a short stick and to strip the insects from it with their mouth. Another example of cultural variation in chimpanzees is the use of tools to crack open nuts. At Gombe, though there are plenty of nuts, the chimps haven't learned to open them, despite an abundance of rocks that would be ideal for the task. In contrast, chimps at Bossou use stone “hammers” to crack open nuts on either stone or wood “anvils.” Chimpanzees at Tai also open nuts in this manner, and they often use pieces of wood as well as rocks for their hammers.
According to the scientists, nut cracking by the Tai chimps provides a good example of a behavior that is learned by young chimps through imitation and then practiced by them as adults. While adult Tai chimps expertly open nuts with their hammers and anvils, the young chimps try pounding on nuts with rotten branches, pieces of fruit, and even chunks of termite mounds. They eventually discover that the stones and hard pieces of wood used by the adults work the best.
Grooming Behavior Among Chimps
Like insect fishing and nut cracking, grooming behavior, which involves one chimpanzee picking insects, bits of dirt, and other matter out of another chimp's coat, varies from group to group. In the mid-1990's, Christophe Boesch, an anthropologist at the Max Planck Institute for Evolutionary Anthropology in Germany, reported that the chimps at Gombe had begun using leaves to squash the small parasites that they pulled from one another's coats. Boesch speculated that the chimps started doing this either because the leaves made it easier to kill the hard-shelled parasites or because the chimps did not like getting their hands messy. In either case, the behavior appeared among a few chimps and then spread throughout the entire troop.
In contrast to the Gombe chimps, Tai chimps remove the parasites, place them on a forearm, smack them with their hand, and then eat them. As with insect fishing, these two approaches to grooming among widely separated groups of chimpanzees are different solutions to the same problem, indicating that group members acquire the particular approach through social learning processes.
“I Want to Mate?” or “I'm Afraid?”
The scientists also proposed several other examples of chimpanzee culture, including an activity known as leaf clipping. In this behavior, a chimp gathers one to five stiff leaves and bites bits of the leaves off without eating them. The biting produces a distinctive ripping sound. This behavior was first observed in the chimpanzees of the Mahale mountains in Tanzania, and the scientists eventually witnessed it at six of the seven study sites—all except Gombe. However, leaf clipping seems to be done for different reasons by different groups.
At Mahale, young male and female chimpanzees clip leaves to attract each other's attention. The behavior and the sound it produces have a meaning that might be translated as, “I want to mate.” But at Bossou, the same leaf-clipping behavior has an entirely different meaning. The researchers working there found that chimpanzees engaged in leaf clipping when they were startled by the observers. Over time, as the chimpanzees became accustomed to the presence of the scientists, they stopped leaf clipping. At Tai, leaf clipping appears to be practiced only by male chimps who also drum on trees with their hands. The males engage in both activities as a means of asserting themselves.
Evidence From Monkeys and Songbirds
Most scientists agree that chimpanzees provide by far the best evidence of animal culture. However, long before this evidence was collected, researchers had reported a possible example of culture in a less advanced primate--monkeys known as macaques that live on Japan's Koshima Island. In 1952, biologists led by Syunzo Kawamura began studying a group of macaques and feeding them sweet potatoes as a way to get close to the macaques for observation.
The sweet potatoes were covered with dirt and sand, which the monkeys routinely rubbed off with their hands. One day, however, a young female named Imo came up with a better idea. She took her dirty potatoes to the water's edge and washed them clean. Within a month, one of Imo's playmates, named Semushi, also began washing potatoes. Three months later, the practice was taken up by Imo's mother, Eba, and a second playmate, Uni. By 1958, potato washing had been adopted by 14 of 15 juveniles in the group and 2 of 11 adults. Even though these monkeys have all since died, the macaques at Koshima Island were still washing potatoes in 2000.
Primates are not the only animals in which scientists have discovered evidence of cultural transmission of behavior. Researchers believe the best nonprimate evidence for culture is found in songbirds, which include thrushes, jays, wrens, warblers, finches, and other common backyard birds. Many studies have indicated that songbirds learn their melodies from parents and neighbors of the same species. Songs within a particular species show regional variations similar to the regional dialects (variant forms of speech) common in human populations. Furthermore, in some bird species, such as the indigo bunting, the nature of songs gradually changes.
Ornithologist (bird expert) Andre Dhondt of Cornell University in Ithaca, New York, notes that the variability of these songs makes them similar to human language, in which new words and new accents appear and change over time. In addition, biologists think of the songs as culture because they represent behaviors that are transmitted through learning and imitation rather than being genetically determined.
Smart Sea Birds, Clever Crows, and Birds With Bachelor Pads
Evidence indicates that other bird behaviors are culturally transmitted as well. For example, oystercatchers—black-and-white wading birds with long, red bills—use different strategies to dine on mussels. Observers have classified these birds into two groups, the “hammerers” and the “stabbers.” The hammerers have bills that are somewhat blunted on the end, while the stabbers have sharp bills. The beak assumes its shape over time as a result of the mussel-eating technique used by the bird.
Hammerers test mussels by tapping on the shells with their beaks, making a sound that reveals the thickness of the shell. If the sound suggests that the shell is thin, the bird breaks it open with hammering blows of its beak, a practice that flattens the end of the bill over the bird's lifetime. Stabbers, on the other hand, look for mussel shells that are already open. When a stabber finds an open shell, it quickly picks out the mussel from within before the shell can close.
Biologists believe that the method of getting into mussel shells favored by particular birds is determined by culture. They base this conclusion on observations of young oystercatchers learning one technique or the other from their parents.
Tool use by jackdaws, small crows that live on the South Pacific island of New Caledonia, is often cited as another example of a behavior that birds learn from one another. In 1996, biologist Gavin R. Hunt of Massey University in New Zealand reported more than 50 different instances of tool use within family groups of jackdaws. The birds made their tools from twigs, stripping the leaves and bark and tapering the ends to a sharp point. They also made hooked twigs that could be used as barbs. The birds held the twigs in their beaks and used them to capture insects from holes in trees and from under leaves. Gavin concluded that the jackdaws exceeded chimpanzees in tool-use skills.
Bowerbirds, which make up 18 species common to Australia and New Guinea, provide more evidence from the bird world of learning through imitation—and perhaps even of purposeful teaching by adults. Male bowerbirds construct elaborate structures, called bowers, to attract females. A bower consists of a large platform woven out of grass, twigs, and other vegetation with walls that form an arch over the structure. The males decorate these “bachelor pads” with various blue or green objects, including berries, shells, flowers, and buttons. Evidence for a cultural role in the building of the bowers comes from observations of young males that visit the bowers of older males early in the mating season. The young males spend a great deal of time observing as the older males tend the bowers and show off their plumage to the females. Groups of young males then work together to build “practice bowers,” taking turns arranging twigs, often clumsily and without success. Occasionally, older males assist the youngsters.
Killer Whales, Ground Squirrels, and Elephants
Yet another possible example of animal culture comes from the ocean and studies of orcas, commonly known as killer whales. Some orcas eat fish, while others dine on marine mammals, including smaller kinds of whales and elephant seals. Orcas, besides varying in their eating habits, also differ in the types of vocalizations they make. The whales of different pods (small groups) make individualized sounds when they meet one another. Whale researcher Hal Whitehead of Dalhousie University in Nova Scotia believes that the variations in eating habits and vocalizations evolved through cultural processes.
For example, in studies of mammal-eating orcas, Whitehead and his colleagues saw behavior that appeared to be a form of teaching. The researchers observed and filmed orcas, which can grow to a length of more than 9 meters (30 feet), crashing up through the surface of the water to catch seals basking on beaches or ice floes. The adult orcas seemed to show the younger ones how to beach themselves in pursuit of a seal and then get back into the water. Orcas, Whitehead commented, “are one of the few species [for which] there is good evidence of adults teaching the young a complex behavior like running up on a beach to catch a seal, which is difficult and dangerous. If they get stuck on the beach, they die.”
Primates, birds, and whales offer the most compelling evidence for culture in animals. However, researchers of animal behavior can cite numerous other species in which behaviors appear to be passed on through imitation and teaching. A number of animal species seem to learn specialized feeding behaviors from their parents. A good example of this is seen with Belding's ground squirrels, group-living rodents of the western United States.
Belding's ground squirrels are well-known among biologists for the alarm calls that females make to warn their offspring and other relatives of impending danger from predators such as hawks. However, studies suggest that female Belding's ground squirrels also teach their offspring which types of foods—including various kinds of seeds, fruits, leaves, stems, and insects—to eat. Some moms are better than others at choosing the most nutritious foods, and they pass these choices along to their pups. These pups are thus more likely to survive to maturity than the offspring of mothers less skilled in foraging.
African elephants are another mammal species in which females seem to play a predominant role in teaching survival skills to youngsters. African elephants live in herds organized around family units consisting of adult females and their offspring. As with Belding's ground squirrels, the young elephants depend upon their mothers to teach them foraging and other activities necessary for survival. The calves in different herds learn to perform these activities in slightly different ways, evidence that these behaviors are transmitted culturally.
Anticulturalist Objections
Although culturalists hail all of these examples as evidence that animals have culture, anticulturalists raise a number of objections to that conclusion. Most notably, the anticulturalist Bennett Galef has argued that neither macaque potato washing nor chimpanzee insect fishing—two examples that culturalists hail as among their strongest evidence for animal culture—qualify as true culture.
According to Galef, potato washing by the macaques, contrary to most reports, may not have been learned through imitation, in which case it could not be considered cultural. He cites research by scientists who visited Koshima Island in the 1970's and observed a caretaker giving potatoes only to those macaques that would wash them. The potatoes were, in effect, a reward for engaging in washing behavior. This sort of process, giving a reward for the performance of a particular behavior, is called conditioning. In conditioning, the scientists rather than the animals are responsible for any changes in the animals' behavior, and so the spread of the new behavior is not a true transmission of animal culture. Galef suggests the possibility that the macaques in the 1950's, following Imo's pioneering trip to the water's edge, may have been influenced by their caretakers to take up potato washing. The caretakers who worked on Koshima at that time, however, denied that they influenced the monkeys in this way.
Another flaw in the case for accepting potato washing as culture, Galef argues, is that a socially imitated behavior would be expected to spread throughout a group rapidly. However, nine years passed before most of the younger macaques in the Koshima troop followed Imo's lead. In light of these factors, Galef concludes that potato washing, if not induced by the caretakers, may at least have been discovered by each individual macaque by chance. In either case, it would not be a cultural behavior.
Galef also argues against a cultural explanation for insect fishing by chimpanzees at Gombe. He proposes that ant and termite fishing might actually be a spontaneous behavior driven more by the chimpanzees' environment than by imitation. He points out that young chimps, who do not fish for insects, often poke at ants with twigs and blades of grass as a form of play. As they get older, the young chimps often pick up the discarded twigs and blades of grass of adults who have been insect fishing and do some probing of their own. Occasionally, they get lucky and get a few nibbles. Learning to fish for insects in this way, says Galef, is more of a rewarded type of behavior than an imitative one and thus does not qualify as culture.
Anticulturalists argue that similar noncultural explanations might be made for many of the other observed types of chimpanzee behavior. As for the examples of supposed cultural behavior in other kinds of animals, anticulturalists propose that some of these behaviors, such as variations in bird-song dialects, can be better explained by genetic differences between populations. And other kinds of behaviors, such as the orcas' seal-hunting strategies and the bower birds' construction behavior, might be the product of trial and error rather than teaching and imitation.
It May Not Be Art, But..
Taken together, however, the weight of evidence from chimpanzees, macaques, birds, orcas, and other species led most observers of animal behavior in 2000 to believe that some animals do indeed possess culture. If animals do have culture, though, it is obviously of a much simpler kind than that possessed by human beings. Compared with the great human cultural achievements of art, science, and technology, animals will never measure up. But perhaps it is wrong to measure animals by human standards. “The ‘culture’ label befits any species, such as the chimpanzee, in which one community can readily be distinguished from another by its unique suite of behavioral characteristics,” said ethologist (expert on animal behavior) Frans B. M. de Waal of the Yerkes Regional Primate Research Center and Department of Psychology at Atlanta's Emory University in an editorial accompanying the 1999 Nature report on chimpanzees. “Biologically speaking, humans have never been alone--now the same can be said of culture.” Scientists expected that future research would clarify the differences as well as the similarities between human and animal culture.