Instinct and Learning
INSTINCT AND LEARNING
Among the most fascinating areas in the biological sciences is ethology, or the study of animal behavior—in particular, the areas of ethology that deal with instinct and learning. Instinct is a stereotyped, or largely unvarying, behavior that is typical of a particular species. An instinctive behavior does not have to be learned; rather, it is fully functional the first time it is performed. On the other hand, learning, in an ethological context, is the alteration of behavior as the result of experience. Clearly, the distinction between instinct and learning revolves around the question of whether an animal, in responding to a specific situation, is acting on the basis of experience or instead is guided by instincts "hardwired" within its brain. The difference would seem to be a simple one, but nothing is simple in the study of instinct and learning. Plenty of gray area exists between pure instinct and genuine learning, and within that gray area is a fascinating concept known as imprinting, or the learning of a behavior at a critical period early in life, such that the behavior becomes permanent.
HOW IT WORKS
The founding fathers of ethology (the study of animal behavior, including its mechanisms and evolution) were the German zoologist Konrad Lorenz (1903-1989) and the Dutch ethologist Nikolaas Tinbergen (1907-1988). In addition to their separate contributions to the field, which we discuss later, the two scientists together developed a theory that animals employ formalized, rigid sequences of action in response to specific stimuli. These sequences they called fixed-action patterns of behavior, or FAPs.
In studying male stickleback fish, Tinbergen discovered an excellent example of a FAP. Males of that species recognize potential competitors, in the form of other stickleback males capable of breeding, by the red stripe on their underside. Tinbergen termed the red stripe a behavioral releaser, or a simple stimulus that brings about a FAP. (A stimulus is any observable fact or event that directly influences the activity or growth of a living organism.)
This particular FAP compels the male stickleback to attack anything red, even when it is not a competitor. Thus, as Tinbergen observed, jealous stickleback males actually would try to attack red British mail trucks when they could see them through the glass of their tanks. Clearly, then, a FAP such as the response to the red stripe is not something that an animal thinks through; rather, it is automatic, almost as though the animal were being acted upon, instead of acting in its own right.
There have been stories and scientific studies of animals seemingly acting above and beyond the call of duty by raising the offspring of other individuals—even those of another species. Tin-bergen, for example, observed and photographed a cardinal feeding baby minnows at water's edge. Such behavior seems altruistic, touching, and even inspiring, yet for all the significance we might be inclined to place on it from our human perspective, it is nothing but a FAP. Most likely the bird had lost its own offspring, and was simply acting on a parental instinct, which caused it to respond to the sight of open, upturned, hungry mouths. It so happened that the open mouths were not those of its offspring at all, but of fish, yet this made no difference in the behavior of the cardinal, acting as it was on an inborn, stereotypic pattern of response.
SURVIVAL-FRIENDLY, CONTROLLED BEHAVIOR.
This is one characteristic of instinct, a concept virtually synonymous with that of the FAP: the creature acting on instinct is not thinking about what it does but is behaving almost as though it were controlled by some outside force. The use of the "outside force" concept perhaps makes instinct sound like something mystical when it is not. On the contrary, instinctive behavior is simply a survival mechanism in the brains of each member of a particular species, developed through countless generations of natural selection.
If a particular behavior helps foster the survival of a species, natural selection favors it. In other words, those individuals of a species who possess the tendency toward a particular survival-friendly behavior are the ones that survive and pass on their genes to others, while those that do not possess this tendency do not. The survival-friendly instinct may be geared toward the survival of the individual, its offspring, or others.
Closely tied to instinct is the innate animal behavior known as a reflex : a simple, inborn, automatic response to a stimulus by a part of an organism's body. Reflexes help animals (including humans) respond quickly to a stimulus, thus protecting them from harm. Again, the animal does not think about what it is doing. If you touch a hot stove or receive an electric shock, you do not decide to pull your hand back: you whip your hand away from the painful stimulus faster than you can blink. As with instinct, a reflex is a survival-friendly behavior over which the animal (in this case, you) has little control.
Innate Versus Learned Behavior
Instinct is innate, meaning that instinctive behaviors and responses are present and complete within the individual at birth. In other words, the individual does not have to undergo any experience to acquire such behaviors. For example, fish have an innate ability to swim, whereas most mammals must learn how to walk. It is fairly easy to identify innate behavior when an animal exhibits it at birth, but in some cases innate behavior manifests only later in life.
In such situations improvements in the creatures' ability to perform an innate behavior may seem to indicate that the animal is learning, when, in fact, another process is at work. For example, chickens exhibit the innate tendency toward pecking as a way of establishing and maintaining a dominance hierarchy. This is the "pecking order," to which people often refer in everyday speech as a metaphor for various hierarchies in human experience, such as those at a workplace. Though pecking is innate, chickens' ability to perform it actually improves as they grow older.
Older chickens display a better aim when pecking than do younger ones, but this does not mean that they have learned from experience. Indeed, one clue that pecking is innate in older chickens is the fact that they uniformly improve in their ability to peck. On the other hand, if they were simply learning, with practice, how to peck more accurately, one could expect that some chickens would exhibit more dramatic improvement than others, in the same way that some humans play basketball (or sing or write poetry) better than others. In fact, what has happened is that the ability to perform an innate behavior simply has improved as a result of growth: as the chickens' eyes and muscles mature, their aim improves, but this has nothing to do with experience per se.
This is one example of the ways in which instinctive and learned behavior can become confused, though in the pecking example there is really no gray area; rather, what is actually an innate behavior merely seems to be a learned one. Yet there truly is a great deal of gray area between instinct and learning. Many behaviors that at first glance might appear purely instinctive can be shown to have an experiential component—that is, an aspect of the behavior has been modified through experience or learning.
A fascinating example of how instinct and learning can be blurred or combined is imprinting, or the learning of a behavior at a critical period early in life, such that the behavior becomes permanent. Lorenz, who first developed the theory of imprinting, noted that newly hatched geese learn to walk by following their parents, but he wondered how they distinguished their parents from all other objects in their environments. He discovered that if he removed the parents from view the first day after the goslings hatched and if he walked in front of the young geese at that point, they would follow him.
From these experiments, Lorenz concluded two things. First of all, during a critical period following birth, goslings follow their parents' movements and learn enough about their parents to recognize them. This critical period is short: if he walked in front of three-day old geese, they were already too old to imprint on him. Second, Lorenz determined that the parents' movement must be a behavioral releaser for imprinting; thus, if the tiny goslings happened to fix on another moving object, they would imprint on that one.
We can see in this example that imprinting has both innnate, or instinctive, and learned components. The tendency to imprint is innate, but if the act of imprinting itself were likewise innate, then it would be the same for all individuals within a species, and this is not the case. The vast majority of goslings will imprint on adult geese, of course, but in an experimental setting (or through some freak accident in nature), it is possible that some other object will come between the offspring and its parents, causing the offspring to imprint on it.
Once imprinting is complete, it brings about numerous consequences that are more or less automatic or inevitable. Yet for all their automatic, inevitable qualities, these consequences are not the result of innate behaviors or instincts but of learned behaviors. Thus, learning is destiny, at least to an extent. The individual's mind, at an early stage, is like wet concrete into which virtually any impression can be made. Once the individual has imprinted on something or someone, however, the concrete begins to set, and it hardens around the impressions made in it.
Instinct at Work
When a kangaroo rat hears a rattling sound, even if that sound comes from a drum or a fan or some otherwise harmless contraption, it performs a lightning-quick escape jump maneuver. Why? Because its brain interprets the rattling sound as that of a rattlesnake ready to strike, and it acts automatically. In other words, the kangaroo rat does not reason out a course of action; it simply moves. Nor is it acting on experience in any way: even if it has never encountered a rattlesnake, it will respond in exactly the same way.
Virtually all instinctive behavior, as we noted earlier, is geared toward preserving the life of the individual or of its offspring, and thus it serves to preserve the life of the species as well. Such is the case with the rat acting to protect itself from the snake, and so, too, with a mother when her young are threatened. People do not normally think of ducks as intimidating creatures, and in most cases they are not, but try stepping anywhere near a mother's ducklings, and watch her response. She will start to hiss, spit, and waddle forward menacingly in such a way as to terrify any would-be intruder. If the outsider is still foolhardy enough to press forward, the duck or goose will readily become a squawking, flapping, biting, pecking army of one. This behavior does not vary from mother to mother but is the same in all instances of mother ducks who perceive a threat to their ducklings—a hallmark of an instinctive action.
AUTOMATIC BEHAVIORS AND RELEASERS.
There is an automatic, almost robotlike character to many an example of instinctive behavior. If an egg rolls out of a goose's nest, the goose stretches her neck until the underside of her bill touches the egg—an action that, like all instinctive ones, clearly is geared toward the survival of her offspring. Suppose someone takes the egg away while the goose is reaching for it: she continues to go through the motion of stretching to retrieve the egg. This may not seem very "smart," but, of course, instinct has nothing to do with intelligence.
Likewise, a spider preparing to lay its eggs spins a silk cocoon in a particular way, always the same and without any regard for outside factors. She begins by building a base plate, then constructs the walls of her cocoon before laying her eggs within it and sealing it with a lid. So rigid are these behavioral patterns that they cannot be altered, even if the spider needs to do so. (It is hard to imagine a spider "wanting" to do something, a term that implies decision-making abilities and a degree of self-awareness common only among higher mammals, particularly humans.)
If the spider is moved physically after she has built the base plate, she nonetheless will set about spinning walls and depositing her eggs, even though there is no base plate to hold them. The eggs, therefore, will fall out of the bottom of the incomplete web, but the spider will continue working as before, building the lid for the top. Fortunately for the spider, she has several cocoons. If she is returned to her original completed base plate as she prepares to spin the next cocoon, she will not use the base plate she already has spun; rather, like a robot, she will start from the very beginning, spinning a new base plate as though the original were not there.
Many of these automatic behaviors are triggered by a releaser. For example, a bright red spot on the bill of an adult gull serves as a releaser to its offspring, which peck on the parent's bill to obtain food. For a female rat in heat, rubbing of her hindquarters acts as a releaser for an instinctive behavior pattern known as lordosis. In lordosis the female flexes her front legs, lowers her torso, raises her rump, and moves the tail to one side. This posture, in turn, acts as a releaser for a male rat, who initiates copulation—yet another example of instinctive behavior as life-preserving. In this case, however, what is being preserved is not the life of an individual but of the entire species, since intercourse yields offspring.
Challenging Situations of Instinct and Imprinting
Instincts are ingrained so deeply that some animals possess what appears to be an instinct for exploiting, or taking advantage of, the instinctive behaviors of other animals. We typically think of parasites as microbes, or at least as no larger than insects, but there are species of bird regarded as parasites, inasmuch as they take advantage of other species. When people speak metaphorically of another person as a "parasite," what they really mean is that the person in question exploits the good behavior of others. A human "parasite" never has to pay for dinner at a restaurant, for instance, because he or she can count on good, decent people always to pick up the tab. Likewise, parasitic bird species, such as the North American cowbird or the European cuckoo, can rely on other species' instinctive tendency to do what all animals (and humans) should do: take care of their own offspring.
Avian parasites lay their eggs in the nest of an unwitting host and then leave, "knowing" instinctively (which is not really the same thing as knowing in the way that humans think of it) that their victims will take care of the eggs. Cow-birds and cuckoos have developed the practice of laying their eggs in the nests of birds that are smaller than they, meaning that their hatchlings will be larger than the victims' offspring. This only adds to the detriment caused by the interlopers: since the parasites' children are larger than the hosts', this triggers a more powerful release of the host parents' instinctive feeding behavior. In other words, the parasites' offspring get more food than the hosts'. As for the parasitic adults, they are long gone, having deposited their young in the care of the hosts.
ERRORS IN IMPRINTING.
The situation of the parasitic bird species is one example of the "dark side" to instinct and learning mechanisms in animals. Other examples include the many possible errors that can occur in imprinting. Such errors arise when an animal either fails to receive an imprint from an appropriate parent figure or receives an imprint from a creature of another species.
In their efforts to establish and maintain their territories and attract females, male birds of a given species learn a particular song. This takes place at a critical period when, as a nestling, the bird hears the song of its father and from this exposure eventually develops its own mature song. The process is a lengthy one: the immature bird does not begin singing until the following spring, when it starts trying to match its own, juvenile song with the one it heard from its father during the critical period.
If during that early critical period, the nestling is prevented from hearing an adult song of its own species, it never will develop a species-typical song, and thus its very life and its ability to propagate (which, in turn, affects the well-being of the entire species) are threatened. The bird may hear the songs of other species, but this does it little good. It appears that there is a strongly instinctive aspect to what the bird can learn during the critical period and also that birds are highly selective toward songs produced by other members of their species. Therefore, it learns either the right song or no song at all.
Why Imprinting Is Crucial
Imprinting is crucial for an animal's development and not only because the act of imprinting helps the animal learn one or another important early function, such as walking. Far beyond what happens to the animal in the first minutes of its life, imprinting will affect its entire destiny both as an individual and as a member of its species. Suppose an animal has imprinted on a creature of another species: this will haunt it for the rest of its life, for instance, determining its choice of a mate and its courtship behavior.
Many species will avoid social contact with animals that are not similar to the one to which they have imprinted. In other words, a duckling that has imprinted properly on its duck parents will want to spend time with other ducks. From the larger perspective of nature and the continuing propagation of life-forms, this is a good thing, because it helps prevent attempts to breed between different species. If, however, through some accident (or as the result of exposure to artificial conditions, such as those in an experiment), an animal has imprinted on an individual of a different species, that animal will attempt to court a member of that other species later in life—usually with disastrous results.
TARZAN THE APE MAN.
In discussing the critical nature of imprinting, we could use all sorts of animal examples, some of which we have discussed. More compelling, however, is the example of a man, albeit a fictional one, who lived among the apes and attempted to become one of them. That man, of course, is Tarzan, creation of the American novelist Edgar Rice Burroughs (1875-1950). First appearing in Tarzan of the Apes (1914) and immortalized in countless novels, movies, comic books, and cartoons, Tarzan is the epitome of the noble savage, or the man at one with nature.
The son of an English lord, the boy is left alone as an infant in Africa after his parents die and is raised by an ape who has lost her own child. The apes name him Tarzan, which, in their language, means "white skin," and he grows up as one of them. Later, he discovers his parents' cabin and the books left there, teaches himself to read, learns English, and begins to uncover the truth of his background. As a grown man, he meets and falls in love with Jane Porter, a beautiful young American who, like his parents when he was infant, was marooned nearby after a shipboard mutiny. Jane helps expose him to civilization, and Tarzan eventually travels to France, the United States, and other far-off lands.
One can find in this astonishing tale antecedents in other rough-and-ready characters from American literature, most notably Buck, the dog turned wolf in Jack London's (1876-1916) novel The Call of the Wild (1903). Buck is a particularly interesting example from the standpoint of biological study, because London, an advocate of Darwin's theory of evolution by natural selection, was attempting to show the common evolutionary thread linking dog and wolf and, by inference, ape and human.
While Burroughs is not so didactic as London, he had a purpose as well, an aim opposite to that of London: to show that a human, thrust by circumstances beyond his control into a world of animals, would assert his humanness. There may even have been a class element to the Tarzan scenario, inasmuch as the young Tarzan is the off-spring of nobility and ultimately proves his noble lineage by rising above his circumstances. (This, too, is a theme quite far removed from the heart of London, who was a socialist.)
All literary analysis aside, is there any truth, from the standpoint of what we know about imprinting, instinct, and learning, to Burroughs's portrayal of Tarzan? The answer is a resounding "no." Assuming that a boy could be raised by apes, he would become socialized as an ape. Appropriately enough, in one story Burroughs shows Tarzan falling in love with a female ape, thinking that he is of the same species. The ape, for her part, recognizes the difference between them and rejects the human in favor of a male ape.
A real-life Tarzan would be human only in a biological sense; otherwise, he would lack virtually all human characteristics. Not only would he be foul smelling (from our perspective) and covered with hair, but he also would be entirely ignorant of human speech or even human thought processes, which have to be learned. Most preposterous of all is the idea that he would find books and recognize them as a mode of communication, let alone teach himself to read them. Suppose that he had been raised as a human but that he had never seen a book or even so much as a written word. Even if he were the most brilliant human being who had ever lived, he would treat the books the way an ape would—as mere objects.
Comparing Humans and Animals
The case of Tarzan provides an appropriate place to close this discussion, with a few words on humans and their place in the context of the larger concepts of instinct, imprinting, and learning. Do humans possess instincts? It appears that we do, inasmuch as we are prone to certain automatic, innate responses. For example, human babies are capable of smiling at the age of four weeks, even though they do not know what a smile "means." On the other hand, humans are not nearly as inclined to instinctive behavior as animals; in general, with higher mammals and especially humans, instinctive characteristics diminish in favor of the capacity to learn.
Our methods of learning are quite different from those of lower animals, who "learn" in ways that do not involve conscious thought. For instance, a snail will pull its head back into its shell when touched, but when it is touched repeatedly with no subsequent harm, the withdrawal response ceases. The snail has experienced habituation, a type of behavior in which an animal develops a tendency to ignore a stimulus that is repeated over and over. Apparently, the snail's nervous system has "learned" that the stimulus is not threatening and so stops the reflex.
This is a far cry from learning as humans experience it, particularly as we move past the first few weeks and months of life. Even from the earliest moments of a human's existence—that is, even in the womb—a human is self-aware in a way that few, if any, animals other than mammals are. Furthermore, the self-awareness of a human from about the age of two years old is far beyond any concept of self possessed by even the highest forms of mammal. From what we can discern, a house cat or even an ape does not experience any thought along the lines of Who am I? or What is my place in the order of things? (Of course, almost everyone who has had a pet has at one time or another believed that a cat or dog was embroiled in such types of philosophical inquiry, but this may be merely anthropomorphism—ascribing human qualities to animals.) By contrast, a two-year-old human already is forming complex judgments about his or her role with regard to Mommy, Daddy, siblings, other relatives, and household pets.
IMPRINTING IN HUMANS.
Whereas humans have fewer instinctive responses than most animals and are far more capable of learning than any other creature, in the area of imprinting we are not so different from cows or even birds. We have discussed the importance of imprinting in birds, but it should be noted that imprinting is at least as critical among hoofed mammals, such as cattle or sheep, since they tend to congregate in large herds where in a young animal could be separated easily from its mother. Likewise, with humans imprinting of some sort is critical.
Humans do not imprint as rigidly as geese do, but it is clear enough that some type of imprinting takes place in the mind of a baby. It is conceivable that Tarzan, having spent a year around his human parents, might retain a few human qualities—but only because it was the first year of his life, when the mind is by definition most impressionable. By the same token, a child that had spent six or seven years around humans would be socialized so thoroughly as a human that he or she probably would retain this human quality even if placed among apes.
From the time of the Greeks, humans have understood that part of what makes us human is contact with other humans. Therefore, an infant separated from its mother for a prolonged period during its first year of life may experience serious mental retardation; irreparable damage and even death may result from a separation of several months. There are all too many terrible stories of people who, as a result of neglect, abuse, or mere misfortune, have been forced to grow up in some form of isolation and have been stunted as a result. Usually, the outcome of this isolation is not nearly as attractive as the noble savage portrayed in literature or in such movies as Nell (1994), in which Jodie Foster plays a young woman who has grown up with little exposure to other humans.
WHERE TO LEARN MORE
Animal Behaviour. University of Plymouth Department of Psychology (Web site). <http://salmon.psy.plym.ac.uk/year1/animbeha.htm>.
Animal Cognition and Learning. Tufts University (Web site). <http://www.pigeon.psy.tufts.edu/psych26/default.htm>.
Dr. P's Dog Training. University of Wisconsin—Stevens Point (Web site). <http://www.uwsp.edu/psych/dog/lib-sci.htm>.
Gould, James L., and Carol Grant Gould. The Animal Mind. New York: Scientific American Library, 1994.
Instinct (Web site). <http://www.a2zpsychology.com/a2z%20guide/instinct.htm>.
Milne, Lorus Johnson, and Margery Joan Greene Milne. The Behavior and Learning of Animal Babies. Chester, CT: Globe Pequot Press, 1989.
Rogers, Lesley J., and Gisela T. Kaplan. Songs, Roars, and Rituals: Communication in Birds, Mammals, and Other Animals. Cambridge, MA: Harvard University Press, 2000.
Tinbergen, Niko. The Study of Instinct. New York: Clarendon Press, 1989.
"Where's My Mommy? Imprinting in the Wild and in Operation Migration—Journey North Whooping Cranes." Annenberg/Corporation for Public Broadcasting (Web site). <http://www.learner.org/jnorth/tm/crane/ImprintingProtocol.html>.
A simple stimulus that brings about a fixed-action pattern of behavior, or FAP.
The study of animal behavior, including its mechanisms and evolution.
Fixed-action patterns of behavior, or strong responses on the part of an animal to particular stimuli. FAP is virtual ly synonymous with instinct.
The learning of a behavior at a critical period early in life, such that the behavior becomes permanent.
A term to describe behaviors that are present and complete within the individual and which require no experience to learn them. For example, fish have an innate ability to swim, whereas humans must learn how to walk.
A stereotyped, or largely unvarying, behavior that is typical of a par ticular species. An instinctive behavior does not have to be learned; rather, it is fully functional the first time it is performed.
The alteration of behavior as the result of experience.
The process whereby some organisms thrive and others perish, depending on their degree of adap tation to a particular environment.
An inborn, automatic response to a stimulus by a part of an organism's body.
See Behavioral releaser.
Any phenomenon (that is, an observable fact or event, such as an environmental change) that directly influences the activity or growth of a living organism.