behavior

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Concept

In biology the term behavior refers to the means by which living things respond to their environments. At first glance, this might seem to encompass only animal behavior, but, in fact, plants display observable behavior patterns as well. One of the principal manifestations of plant behavior is tropism, a response to a stimulus that acts in a particular direction, thus encouraging growth either toward or away from that stimulus. Behavior in plants is primarily a matter of response to stimuli, which may be any one of a variety of influences that derive either from inside or outside the organism. Response to stimuli is automatic, and even humans are capable of making these types of programmed responses. In most cases, behaviors in organisms are designed to ensure their survival. Such is the case, for instance, with the complex of behaviors known as territoriality, whereby animals defend what they perceive to be their own.

How It Works

Stimulus and Response

A stimulus is any phenomenon that directly influences the activity or growth of a living organism. Phenomenon, meaning any observable fact or event, is a broad term and appropriately so, since stimuli can be of so many varieties. Chemicals, heat, light, pressure, and gravity all can serve as stimuli, as indeed can any environmental change. Nor are environmental changes limited to the organism's external environment. In some cases its internal environment can act as a stimulus, as when an animal reaches the age of courtship and mating and responds automatically to changes in its body.

All creatures, even humans, are capable of automatic responses to stimuli. When a person inhales dust, pepper, or something to which he or she is allergic, a sneeze follows. The person may suppress the sneeze (which is not a good practice, since it puts a strain on blood vessels in the head), but this does not stop the body from responding automatically to the irritating stimulus by initiating a sneeze. Similarly, plants respond automatically to light and other stimuli in a range of behaviors known collectively as tropisms, which we explore later in this essay.

Innate and Learned Behavior

Not all responses to stimuli are automatic, however. Certainly not all behavior on the part of higher animals is automatic, though, as we have noted, even humans are capable of some automatic responses. In general, behavior can be categorized as either innate (inborn) or learned, but the distinction is frequently unclear. In many cases it is safe to say that behavior present at birth is innate, but this does not mean that behavior that manifests later in life is learned. (Later in this essay we look at an example of this behavior as it relates to chickens and pecking.)

Behavior is considered innate when it is present and complete without any experience whereby it was learned. At the age of about four weeks, human babies, even blind ones, smile spontaneously at a pleasing stimulus. Like all innate behavior, babies' smiling is stereotyped, or always the same, and therefore quite predictable. Plants, protista (single-cell organisms), and animals that lack a well-developed nervous system rely on innate behavior. Higher animals, on the other hand, use both innate and learned behavior. A fish is born knowing how to swim, whereas a human or a giraffe must learn how to walk.

Ethology

Ethology is the study of animal behavior, including its mechanisms and evolution. The science dates back to the British naturalist Charles Darwin (1809-1882), who applied it in his research concerning evolution by means of natural selection (see Evolution). Darwin presented many examples to illustrate the fact that, in addition to other characteristics of an organism, such as its morphologic features or shape, behavior is an adaptation to environmental demands and can increase the chances of species survival.

The true foundations of ethology, however, lie in the work of two men during the period between 1930 and 1950: the Austrian zoologist Konrad Lorenz (1903-1989) and the Dutch ethologist Nikolaas Tinbergen (1907-1988). Together with the Austrian zoologist Karl von Frisch (1886-1982), most noted for his study of bee communication and sensory perception, the two men shared the 1973 Nobel Prize in physiology or medicine.

Lorenz and Tinbergen, who together are credited as founders of scientific ethology, contributed individually to the discipline and, during the mid-twentieth century, worked together on a theory that animals develop formalized, rigid sequences of action in response to specific stimuli. According to Lorenz and Tinbergen, animals show fixed-action patterns (FAPs) of behavior which are strong responses to particular stimuli. Later in this essay, we look at examples of FAPs in action. In addition, Lorenz put forward the highly influential theory of imprinting, discussed briefly in this essay and in more detail elsewhere (see Instinct and Learning).

Behaviorism and Conditioning

The development of ethology by Lorenz and Tin-bergen occurred against the backdrop of the rise of the behaviorist school in the realms of philosophy, psychology, and the biological sciences. This school of thought had its roots in the late nineteenth century, with the writings of a number of philosophers and psychologists as well as practical scientists, such as the Russian physiolo-gist Ivan Pavlov (1849-1936). Pavlov showed that an animal can be trained to respond to a particular stimulus even when that stimulus is removed, so long as the stimulus has been associated with a secondary one.

Pavlov began his now famous set of experiments by placing powdered meat in a dog's mouth and observing that saliva flowed into the mouth as a reflex reaction to the introduction of the meat. He then began ringing a bell before he gave the dog its food. After doing this several times, he discovered that the dog salivated merely at the sound of the bell. Many experiments of this type demonstrated that an innate behavior can be modified, and thus was born the scientific concept of conditioning, or learning by association with particular stimuli.

The variety of conditioning applied by Pavlov, known as classical conditioning, calls for pairing a stimulus that elicits a specific response with one that does not, until the second stimulus elicits a response like the first. Classical conditioning is contrasted with operant conditioning, which involves administering or withholding reinforcements (that is, rewards) based on the performance of a targeted response.

Operant Conditioning

During operant conditioning, a random behavior is rewarded and subsequently retained by an animal. According to operant conditioning theory, if we want to train a dog to sit on command, all we have to do is wait until the dog sits and then say, "Sit," and give the dog a biscuit. After a few repetitions, the dog will sit on command because the reward apparently reinforces the behavior and fosters its repetition.

Human parents apply operant conditioning when they admonish their offspring with such phrases as "You can't watch TV until you've cleaned your room." Likewise, young chimpanzees learn through a form of operant conditioning. By observing their parents, young chimps learn how to strip a twig and then use it to pick up termites (a tasty treat to a chimpanzee) from rotten logs. Their behavior thus is rewarded, an example of the way that operant conditioning enables animals to add new, noninherited forms of behavior to their range of skills.

Though the theory of operant conditioning goes back to the work of the American psychologist Edward L. Thorndike (1874-1949), by far its most famous proponent was another American psychologist, B. F. Skinner (1904-1990). In applying operant conditioning to human beings, Skinner and his followers took the theory to extremes, maintaining that humans have no ideas of their own, only conditioned responses to stimuli. Love, courage, faith, and all the other emotions and attitudes that people hold in high esteem are, according to this school of thought, simply a matter of learned responses, rather like a parrot making human-like sounds to earn treats. This extreme form of behaviorism is no longer held in high regard within the scientific or medical communities.

Real-Life Applications

Behavior in Plants

As noted earlier, the term behavior would seem at first glance to apply only to animals and not to plants. Certainly the majority of attention in behavioral studies, outside the realm of humans, is devoted to ethology, but plants are not without their observable behavioral characteristics. These features primarily manifest in the form of tropism, a response to a stimulus that acts in a particular direction, thus encouraging growth either toward or away from that stimulus. Tropism primarily affects members of the plant kingdom, though it has been observed in algae and fungi as well.

Though the word tropism itself may be unfamiliar to most people, the phenomenon itself is not. There are plenty of opportunities in daily life to observe the response of plants to energy, substances, or forms of stimulation. For example, perhaps you have noticed the way that trees or flowers grow toward sunlight, even bending in their growth if it is necessary to reach the energy source. Similarly, plants in a parched region are likely to develop roots directed laterally toward a water source.

Among the various forms of tropism are phototropism (response to light), geotropism (response to gravity), chemotropism (response to particular chemical substances), hydrotropism (response to water), thigmotropism (response to mechanical stimulation), traumatropism (response to wounds), and galvanotropism or electrotropism (response to electric current). Most of these types involve growth toward a stimulus, a phenomenon known as positive growth, or orthotropism. Plants tend to grow toward light or water, for instance. On the other hand, some kinds of stimuli tend to evoke diatropism, or growth away from the stimulus. Such is bound to be the case, for instance, with traumatropism and electrotropism.

Tropism, along with movement due to changes in water content, is one of the two principal forms of innate behavior on the part of plants. In general, stems and leaves experience positive phototropism, as they grow in the direction of a light source, the Sun. At the same time, roots exhibit positive gravitropism, or growth toward the gravitational force of Earth, as well as positive hydrotropism, since they grow toward water sources below ground. On the other hand, a plant may move in a specific way regardless of the direction of the stimulus. Such movements are temporary, reversible, and result from changes in the water pressure inside the plant.

Animal Behavior

An excellent example of an innate animal behavior, and one in which humans also take part, is the reflex. A reflex is a simple, inborn, automatic response to a stimulus by a part of an organism's body. The simplest model of reflex action involves a receptor and sensory neuron and an effector organ. Such a mechanism is at work, for instance, when certain varieties of coelenterate (a phylum that includes jellyfish) withdraw their tentacles.

More complex reflexes require processing interneurons between the sensory and motor neurons as well as specialized receptors. These neurons send signals across the body, or to various parts of the body, as, for example, when food in the mouth stimulates the salivary glands to produce saliva or when a hand is pulled away rapidly from a hot object.

Reflexes help animals respond quickly to a stimulus, thus protecting them from harm. By contrast, learned behavior results from experience and enables animals to adjust to new situations. If an animal exhibits a behavior at birth, it is a near certainty that it is innate and not learned. Sometimes later in life, however, a behavior may appear to be learned when, in fact, it is a form of innate behavior that has undergone improvement as the organism matures.

For example, chickens become more adept at pecking as they get older, but this does not mean that pecking is a learned behavior; on the contrary, it is innate. The improvement in pecking aim is not the result of learning and correction of errors but rather is due to a natural maturing of muscles and eyes and the coordination between them.

Faps

In studying fixed-action patterns of behavior, or FAPs, Lorenz and Tinbergen observed numerous interesting phenomena. Male stickleback fish, for example, recognize potential competition—other breeding stickleback males—by the red stripe on their underside and thus engage in the FAP of attacking anything red on sight. Tinbergen discovered that jealous stickleback males were so attuned to the red stripe that they tried to attack passing British mail trucks, which were red, when they could see them through the glass of their tanks. Tinbergen termed the red stripe a behavioral releaser, or a simple stimulus that brings about a FAP.

Once a FAP is initiated, it continues to completion even if circumstances change. If an egg rolls out of a goose's nest, the goose stretches her neck until the underside of her bill touches the egg. Then she rolls the egg back to the nest. If someone takes the egg away while she is reaching for it, the goose goes through the motions anyway, even without an egg. Not all animal behavior is quite so predictable, however. In contrast to FAPs are complex programmed behavior patterns, which comprise several steps and are much more complicated. Birds making nests or beavers building dams are examples of complex programmed behavior.

Imprinting

As we noted earlier, Lorenz initiated the study of a learning pattern that came to be known as imprinting. Witnessed frequently in birds, imprinting is the learning of a behavior at a critical period early in life, such that the behavior becomes permanent. The very young bird or other organism is like wet concrete, into which any pattern can be etched; once the concrete has dried, the pattern is set.

Newly hatched geese are able to walk. This is something they learn the moment they are hatched, and they do so by following their parents. But how, Lorenz wondered, do young geese distinguish 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. This tactic did not work if he waited until the third day after hatching, however.

Lorenz concluded that during a critical period following birth, the goslings follow their parents' movement and learn enough about their parents to recognize them. But since he also had determined that young geese follow any moving object, he reasoned that they first identify their parents by their movement, which acts as a releaser for parental imprinting. (Imprinting is discussed further in Instinct and Learning.)

Interactive Behavior

Much of an animal's behavior (this is true of the human animal as well) takes place in interaction with others. This interaction may include rudimentary forms of communication, such as bee dances, studied by Lorenz and Tinbergen's colleague Frisch. As he showed in perhaps the most important research of his career, bees communicate information about food supplies, including their direction and the distance to them, by means of two different varieties of "dance," or rhythmic movement. One is a circling dance, which informs the other bees that food is near (about 250 ft., or 75 m, from the hive), and the other is a wagging dance, which conveys the fact that food is farther away.

There are numerous other forms of communication using one or more sense organs. Birds hear each other sing, a dog sees and hears the spit and hiss of a cornered cat, and ants lay down scent signals, or pheromones, to mark a trail that leads to food. This is only one level of interactive behavior, however. Quite a different variety of interaction is courtship, discussed in Reproduction. Other forms of interactive behavior include the establishment of an animal's territory, a subject we discuss at the conclusion of this essay.

Life in Communities

Interactive behavior comes into play when animals live in close proximity to one another. Certainly there are benefits to group life for those species that practice it: the group helps protect individuals from predators and, through cooperation and division of labor, ensures that all are fed and sheltered. In order to be workable, however, a society must have a hierarchy. Thus, in a situation quite removed from the human ideals of freedom and democracy, insect and animal societies are ones in which every creature knows its place and sticks to it.

Bees, ants, and termites live in complex communities in which some individuals are responsible for finding food, others defend the colony, and still others watch over the offspring. In such a highly organized society, a dominance hierarchy or ranking system helps preserve peace and discipline. Chickens, for example, have a pecking order from the most dominant to the most submissive. Each individual knows its place in the order and does not challenge individuals of higher rank. This, again, is quite unlike humans, who at least occasionally step out of line and challenge bullies; by contrast, that never happens with chickens (fittingly enough).

Territoriality

Almost everyone has seen a dog "mark its territory" by urinating on a patch of ground or has watched a cat arch its back in fury at an intruder to what it perceives as its territory. In so doing, these household pets are participating in a form of behavior that cuts across the entire animal kingdom: territoriality, or the behavior by which an animal lays claim to and defends an area against others of its species and occasionally against members of other species as well.

The physical size of the territory defended is extremely varied. It might be only slightly larger than the animal itself or it might be the size of a small United States county. The population of the territory might consist of the animal itself, the animal and its mate, an entire family, or an entire herd or swarm. Time is another variable: some animals maintain a particular territory year-round, using it as an ongoing source of food and shelter. Others establish a territory only at certain times of the year, when they need to do so for the purposes of attracting a mate, breeding, or raising a family.

Territorial behavior offers several advantages to the territorial animal. An animal that has a "home ground" can react quickly to dangerous situations without having to seek hiding places or defensible ground. By placing potential competitors at spaced intervals, territoriality also prevents the depletion of an area's natural resources and may even slow down the spread of disease. Furthermore, territorial behavior exposes weaker animals (which are unable to defend their territory) to attacks by predators and thus assists the process of natural selection in building a stronger, healthier population.

Examples of Territories

A territory established only for a single night, for the sole purpose of providing the animal or animals with a place to rest, is known as a roost. Even within the roost, there may be a battle for territory, since not all spots are created equal. Because roosting spots near the interior are the safest, they are the most highly prized.

Another type of specialized territory is the lek, used by various bird and mammal species during the breeding season. Leks are the "singles bars" of the animal world: here animals engage in behavior known as lekking, in which they display their breeding ability in the hope of attracting a mate. Not surprisingly, leks are among the most strongly defended of all territories, since holding a good lek increases the chances of attracting a mate. Like the singles-only communities that they mimic, leks are no place for families: generally of little use for feeding or bringing up young, the lek usually is abandoned by the animal once it attracts a mate or mates.

Threatening Displays

An animal has to be prepared to defend its territory by fighting off invaders, but naturally it is preferable to avoid actual fighting if a mere display of strength will suffice. Fighting, after all, uses up energy and can result in injury or even death. Instead, animals rely on various threats, through vocalizations, smells, or visual displays.

The songs of birds, the drumming of woodpeckers, and the loud calls of monkeys may seem innocuous to humans, but they are all warnings that carry for long distances, advertising to potential intruders that someone else's territory is being approached. As noted earlier, many animals, such as dogs, rely on smells to mark their territories, spraying urine, leaving droppings, or rubbing scent glands around the territories' borders. Thus, an approaching animal will be warned off the territory without ever encountering the territory's defender. Or, if the invader is unfortunate enough to have trespassed on a skunk's territory, it may get a big blast of scent when it is too late to retreat.

Suppose an animal ignores these warnings, or suppose, for one reason or another, that two animals meet nose to nose at the boundaries of their respective territories. Usually there follows a threatening visual display, often involving exaggeration of the animals' sizes by the fluffing up of feathers or fur. The animals may show off their weapons, whether claws or fangs or other devices. Or the two creatures may go through all the motions of fighting without ever actually touching, a behavior known as ritual fighting.

Fighting

The degree to which a creature engages in these displays of bravado helps define its territory. If the creature perceives that it is at the center of its own territory and is being attacked on home ground, it will go into as threatening a mode as it can muster. If, on the other hand, the animal is at the edge of its territorial boundaries, it will be much more halfhearted in its efforts at intimidation. As with humans, few animals want to fight when there is nothing really at stake. Also like humans, animals many times may seem to be spoiling for a fight without actually fighting, such that when a fight does break out, it is an aberration. This typically happens only in overcrowded conditions, when resources are scarce—again, not unlike the situation with humans.

Late in his career, Lorenz devoted himself to studying human fighting behavior. In Das sogenannte Böse (On Aggression, 1963), he maintained that fighting and warlike behavior are innate to human beings but that they can be unlearned through a process whereby humans' basic needs are met in less violent ways. Just as fighting in animal communities has its benefits, Lorenz maintained, inasmuch as it helps keep competitors separated and enables the larger group to hold on to territory, so fighting among humans might be directed toward more useful means. As discussed in Biological Communities, it is possible that sports and business competition in the human community provides a more peaceful outlet for warlike instincts.

Where to Learn More

Animal Behavior Resources on the Internet. Nebraska Behavioral Biology Group (Web site). <http://cricket.unl.edu/Internet.html>.

Applied Ethology (Web site). <http://www.usask.ca/wcvm/herdmed/applied-ethology/>.

Dugatkin, Lee Alan. Cheating Monkeys and Citizen Bees: The Nature of Cooperation in Animals and Humans. New York: Free Press, 1999.

Ethology: Animal Behavior (Web site). <http://www.nua-tech.com/paddy/ethology.shtml>.

"Growth Movements, Turgor Movements, and Circadian Rhythmics." Department of Biology, University of Hamburg (Germany) (Web site). <http://www.biologie.uni-hamburg.de/b-online/e32/32c.htm>.

Hart, J. W. Light and Plant Growth. Boston: Unwin Hyman, 1988.

Hauser, Marc D. Wild Minds: What Animals Really Think. New York: Henry Holt, 2000.

Hinde, Robert A. Individuals, Relationships, and Culture: Links Between Ethology and the Social Sciences. New York: Cambridge University Press, 1987.

Immelmann, Klaus, and Colin Beer. A Dictionary of Ethology. Cambridge, MA: Harvard University Press, 1989.

Tropisms (Web site). <http://www.ultranet.com/~jkimball/BiologyPages/T/Tropisms.html>.

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In object technology, the processing that an object can perform.

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noun

1. The manner in which one behaves: action (often used in plural), comportment, conduct, deportment, way. See be.
2. The way in which a machine or other thing performs or functions: functioning, operation, performance, reaction, working (often used in plural). See action/inaction, machine.

What is behavior? A dictionary definition reveals that behavior consists of our activities and actions, especially actions toward one another. As such definitions suggest, many behavioral terms have meaning only in social comparisons: We identify others as contentious, courteous, or conscientious only by their actions in social contexts. A long-standing question in science and in everyday affairs inquires about the causes of individual differences in behavior: Why are some people gregarious extroverts and others timid, shy introverts?

Behavior genetics is a hybrid area of science, at the intersection of human genetics and psychology. Its focus is on how genes and environments contribute to differences in behavior. It is a young discipline. A book that gave the field its name was published in 1960, and a decade later the Behavior Genetics Association was founded. For a time, most behavior genetics research was an effort to show that the term was not itself an oxymoron—that variations in genes do contribute to individual differences in behavior. Now, as a result of that research, the relevance and importance of genetic variation to individual differences in behavior are widely accepted, and the challenging task is to identify specific gene-behavior pathways. In this entry, we will review the methods used to identify such pathways and then focus on one set of behaviors, use and abuse of alcohol, as a model for the study of genetic and environmental influences.

Twin and Adoption Studies

To determine whether variation in some dimension of behavior is heritable (whether behavioral differences are, in some part, due to genetic differences between people), human researchers use family, twin, and adoption designs. The first step in determining whether a behavior is influenced by genes is to establish that it aggregates or "runs" in families. Similarities in behavioral characteristics among family members suggest that genes influence the trait, but they cannot conclusively demonstrate genetic influence, because family members share their experiences (i.e., their environments) as well as their genes.

Twin and adoption studies allow one to tease apart the effects of genes and environments. Twin studies compare the patterns of behavioral characteristics between identical, or monozygotic (MZ), and fraternal, or dizygotic (DZ), twins. MZ twins share 100 percent of their genetic information, whereas DZ twins share, on average, one-half, just like non-twin siblings. Thus, the presence of greater behavioral similarities between MZ twins than DZ twins suggests that genetic factors contribute to those behaviors.

Adoption studies compare whether an adopted child is more similar behaviorally to the child's adoptive parents (with whom environments, but not genes, are shared) or to the child's biological parents (with whom genes, but not environments, are shared). Twin and adoption techniques have been used to demonstrate that nearly all behavior is under some degree of genetic influence, and, in the context of the Human Genome Project, behavior genetics has attracted great interest and some controversy.

Complex Genetics

New techniques allow behavior geneticists to ask not just whether a behavior is under genetic influence, but also what specific genes are involved. To identify genes involved in behavior, investigators use genetic markers—stretches of DNA that differ among individuals. One can either use genetic markers that are evenly spaced on all chromosomes, to search for genes influencing the behavior that are located anywhere in the genome (called genomic screening), or one can test markers at a specific gene believed to be, on theoretical grounds, involved in the behavior (called the candidate gene approach).

The idea behind these analyses is that if a particular gene is involved in the behavior, then people who are more alike with respect to the behavior will be more likely to share the same stretch of DNA that is at or near the gene. The difficulty in searching for genes involved in behavior is that there is no one-to-one correspondence between carrying a particular gene and exhibiting a particular behavior. There are no genes for behavior; there are only genes that influence behavior. Any particular behavior is a complex trait that involves more than one gene and is influenced by the environment as well.

For example, having a particular gene may make a person more likely to have problems with alcohol, but it does not determine whether or not the person will be an alcoholic. Some individuals will carry genes predisposing them to alcohol abuse but will never exhibit any problems, because they choose to abstain from alcohol. Other individuals will exhibit obvious alcohol problems, but will not carry the particular genes known to be involved.

This is because a large number of genes are risk-relevant for use and abuse of alcohol, and each has only a very small effect. Different genes may be acting in different individuals. And genes interact with each other and with the environment. Thus, individual outcomes result from a complex and ill-understood mixture of both genetic and environmental risk factors. That very complexity creates the diverse nature of human behavior. Indeed, it is what makes us uniquely human, but it also makes finding genes involved in human behavior extraordinarily difficult.

Animal Models

Because of this complexity, some investigators use animal models to complement human studies. Like humans, mice and rats differ in a variety of behavioral characteristics, including levels of alcohol use and tolerance or sensitivity to its effects. Animal studies allow breeding strategies that cannot be performed in humans. One approach that is commonly used in animal studies takes advantage of natural variation in behavior. Different strains of mice differ not only in coat color but also in preference for alcohol.

Under one of the most commonly used breeding strategies, animals from each of the behaviorally different mouse lines are allowed to mate with each other. Assuming the parents from each strain have different versions of genes contributing to alcohol use, subsequent generations of offspring will have different combinations of the genes contributing to the alcohol use and will display wide variation in their alcohol use. Such samples can be used to perform genetic studies searching for genes involved in the behavior, much like those described in humans: Animals more alike in their drinking behavior should be more likely to have inherited common stretches of DNA involved in the behavior.

One advantage of using animals is that the factors contributing to alcohol use in mice and rats are thought to be much simpler than the processes contributing to abuse in humans. Another is that animals' experience with alcohol can be experimentally controlled. Other strategies that are used in animals include inducing mutations or "knocking out" particular genes and studying the resultant aberrant behavior. If altering a particular gene consistently causes an alteration in a given behavior, the gene is likely involved in that behavior.

Alcoholism in Humans

The techniques available for human research are more limited, and many questions remain. Although behavior geneticists now possess the techniques to identify genetic influence and to begin to identify specific genes, questions remain regarding which behaviors, actions, and activities of people are the best candidates for behavior-genetic study.

Again, alcohol use and abuse provide an illustration. Alcoholism is a major social and medical problem in the United States and in most of the world. It is estimated that 10 percent of men and 4 percent of women in the United States experience alcohol dependency, at a cost of billions of dollars and 100,000 lives annually. Because use of alcohol is typically part of social interactions, familial (and possibly genetic) factors would be expected to contribute to variation in drinking.

But where shall we begin its study? Perhaps with diagnosed alcoholism? Most adults in our society use alcohol, yet only a fraction of them ever experience clinical symptoms of alcoholism. Perhaps we should begin much earlier, studying the decision to begin drinking? Obviously, one cannot become alcoholic without initiating drinking and then drinking large quantities regularly and with high frequency. Or perhaps much earlier yet, for behavioral predictors of alcoholism can be identified years before alcohol is first consumed.

Such predictors are apparent in early childhood, in behaviors evident to the children's parents, teachers, and peers. Long-term (i.e., longitudinal) studies conducted in several countries suggest that, as early as kindergarten and elementary school, behavioral ratings made by parents, teachers, or classmates distinguish children who are more likely to abuse alcohol later, in adolescence and early adulthood. Children who were impulsive, exploratory, excitable, curious, and distractible—and those who were less cautious, less fearful, less shy, and less inhibited—have a much greater risk of adult alcoholism than do children without those characteristics.

Twin studies have demonstrated that additive genetic variance, as well as familial-environmental influences, significantly contributes to the childhood behaviors that play a central role in the development of alcoholism risk. So, to understand the development of alcoholism, one must appreciate the complex developmental influences that affect children years before they first consume alcohol. Those influences reflect the interactions of dispositional differences in children's behavior with variations in their familial, social, and school environments.

Twin Studies of Alcoholism

That risk-related behaviors are evident early in life, remain stable into adolescence, and are associated with a family history of alcoholism suggests that those behaviors are, at least in part, of genetic origin. To establish that, researchers must use genetically informative study designs.

One approach is to study child or adolescent twins and their parents. Several such studies, which specifically assess the initiation of alcohol use and the transition to alcohol abuse, are being conducted throughout the world. We illustrate with two ongoing studies from Finland.

One, "FinnTwin12," is a study of approximately 2,800 twin pairs and their parents. The twins represent all pairs from five consecutive twin-birth cohorts (1983-1987) who were entered into the study as they reached age twelve (1995-1999), when behavioral ratings by teachers and parents were obtained on all participating pairs.

The ratings include multidimensional scales (i.e., scales that rate various characteristics) of behaviors associated with increased alcoholism risk. Two years later, at age fourteen, the twins were followed up, and, while most reported abstinence, about one-third were then using alcohol.

What predicts drinking or abstaining at age fourteen? Genetic factors played a role only among twin sisters, perhaps reflecting their more accelerated pubertal maturation, and environmental effects shared by twin siblings accounted for most of the variation in drinking or abstaining at this age. Differences that twins attributed to their home environments (e.g., in parental monitoring, support, and understanding) and differences in teachers' ratings of twins' behavior at age twelve (in problem behaviors of aggressiveness, impulsivity, and inattention) differentiated those who were drinking from those still abstaining at fourteen.

But once drinking is initiated, genetic effects become evident in individual differences in frequency and quantity of consumption and in behavioral problems that then result. "FinnTwin16," another study of five consecutive, complete birth cohorts of Finnish twins, illustrates. These twins were first studied as they reached age 16, with follow-up twelve and thirty months later, at ages 17 and 18^1/2. At age 16, about 25 percent had remained abstinent.

Of 2,810 twin pairs, both twins in 459 pairs (16.3%) were abstaining, co-twins in 1,964 pairs (69.9%) had concordantly begun drinking by age sixteen, and only 387 pairs were discordant, with one twin drinking and the other abstaining. Concordance is the co-occurrence of the behavior in the twin pair (e.g., both drinking or both not drinking). Overall concordance exceeded 85 percent, regardless of the twins' gender or zygosity.

There was extremely high familial aggregation for alcohol use or abstinence at age sixteen, additional evidence that genes play little role in abstinence or initiation. But thirty months later, individual abstinence had dropped to 10 percent, concordance among twin pairs had declined considerably, and genetic factors increasingly influenced the frequency and quantity of an adolescent's alcohol consumption. MZ twins were significantly more similar in drinking frequency than were DZ twins. The influence of genetic factors increases over time, with increasing experience with alcohol, and the differences between MZ and DZ twins becomes greater at each follow-up.

Regional residency moderates parental and sibling influences on adolescent drinking. Where abstinence is relatively rare, as in the large cities of Finland, siblings have greater effects on one another. Conversely, the protective effect of parental abstinence on that of their adolescent twin children was more evident in sparsely populated rural areas of the country, where abstinence was more prevalent. And, most interestingly, genetic factors exerted a larger role in urban settings than in rural settings from age 16 through the follow-up at age 18^1/2. Common environmental factors assumed greater importance in rural settings.

Such results suggest that environments moderate the impact of genetic effects across many dimensions of behavior. But what aspects of the environment matter? In an analysis of results at age 18^1/2, we demonstrated that specific characteristics of rural and urban environments moderate the effects of genes on drinking behavior. In areas with proportionately more young adults, genetic effects were nearly five times more evident than in communities with relatively few young adults. Thus, dramatic differences in the magnitude of genetic effects can be demonstrated across communities at environmental extremes of specific risk-relevant characteristics.

Complex Behaviors, Complex Causes

Thus, for use and abuse of alcohol, we know that the importance of genetic and environmental effects changes with sequencing in the use and abuse of alcohol, from abstinence or initiation to frequency of regular consumption, to problems associated with consumption, and ultimately, to diagnosed alcoholism and end-organ damage from the cumulative effects of alcohol. Similar stories could be told for many other behaviors of interest. Thus, for the major psychopathologies, from depression and schizophrenia in adults to attention deficit disorder in children or eating disorders in adolescents, genetic influences are invariably part of the story but never the whole story.

Genetic effects are always probabilistic and not deterministic. And the action of genes on behavioral outcomes is likely to be indirect. So we conclude with the same message with which we began: There are no genes for behavior, but behavioral development always represents an exquisite interplay between genes and environments. Gene-behavior correlations are modest and nonspecific; they alter risk but rarely determine outcome. Genes represent dispositions, not destinies.

Bibliography

Dick, Danielle M., and Richard J. Rose. "Behavior Genetics: What's New? What's Next?" Current Directions in Psychological Science 11 (2002): 70-74.

Rose, Richard J. "A Developmental Behavior-Genetic Perspective on Alcoholism Risk." Alcohol Health and Research World 22 (1998): 131-143.

Rose, Richard J., et al. "Drinking or Abstaining at Age 14? A Genetic Epidemiological Study." Alcoholism: Clinical and Experimental Research 25 (2001): 1594-1604.

—Richard J. Rose and Danielle M. Dick

A cynical view of the world by Ambrose Bierce

n.

Conduct, as determined, not by principle, but by breeding. The word seems to be somewhat loosely used in Dr. Jamrach Holobom's translation of the following lines from the Dies Irae:

        Recordare, Jesu pie,
        Quod sum causa tuae viae.
        Ne me perdas illa die.
    
    Pray remember, sacred Savior,
    Whose the thoughtless hand that gave your
    Death-blow.  Pardon such behavior.

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IN BRIEF: Of or relating to a manner of conducting oneself.

As we discuss the behavioral approach, for the most part we will assume that the mind is a "black box" that we cannot see into. — http://chiron.valdosta.edu/whuitt/col/behsys/behsys.html

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!

sign description: Initialized sign: The sign ACT is done with a B handshape.

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Quotes:

"The test of one's behavior pattern; relationship to society, relationship to one's work, relationship to sex." - Alfred Adler

"The only normal people are the one's you don't know very well." - Joe Ancis

"Of course, behaviorism works. So does torture. Give me a no-nonsense, down-to-earth behaviorist, a few drugs, and simple electrical appliances, and in six months I will have him reciting the Athanasian Creed in public." - W. H. Auden

"Our natures are a lot like oil, mix us with anything else, and we strive to swim on top." - Francis Beaumont

"With a gentleman I am always a gentleman and a half, and with a fraud I try to be a fraud and a half." - Otto Von Bismarck

"It is the unseen and the spiritual in people that determines the outward and the actual." - Thomas Carlyle

See more famous quotes about Behavior

Pertaining to behavior.

• b. disorders — see vice.
• b. seizure — see psychomotor seizure.
• b. therapy — aims to modify patterns of behavior so that they are acceptable to the owner.

n

The manner in which a person acts or performs; any or all of the activities of a person, including physical action learned and unlearned, deliberate or habitual.

For a list of words related to behavior, see:

• Environment, Ecology, and Animal Behavior - behavior: organism’s observable responses to environment and stimuli
• Mental States, Processes, and Behavior - behavior: actions and activities of humans and animals

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See words rhyming with "behavior."

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Common misspelling(s) of behavior

• behavour

Dansk (Danish)
n. - opførsel, adfærd, optræden

idioms:

• behavioural therapy    adfærdsterapi

Nederlands (Dutch)
gedrag

Français (French)
n. - comportement, conduite

idioms:

• behavioural therapy    thérapie de comportement

Deutsch (German)
n. - Verhalten, Benehmen, Verhaltensweise

idioms:

• behavioural therapy    Verhaltenstherapie

Ελληνική (Greek)
n. - συμπεριφορά, διαγωγή, στάση, φέρσιμο, τρόποι

idioms:

• behavioural therapy    θεραπεία συμπεριφοράς

Italiano (Italian)
comportamento

idioms:

• behavioural therapy    terapia comportamentale

Português (Portuguese)
n. - comportamento (m)

idioms:

• behavioural therapy    terapia (f) comportamental

Русский (Russian)
поведение, отношение к кому-либо, обращение с кем-либо

idioms:

• behavioural therapy    поведенческая терапия

Español (Spanish)
n. - comportamiento, conducta, proceder

idioms:

• behavioural therapy    terapia del comportamiento

Svenska (Swedish)
n. - uppförande, beteende, sätt, skick, hållning

中文（简体）(Chinese (Simplified))
行为, 习性, 举止

idioms:

• behavioural therapy    行动治疗

中文（繁體）(Chinese (Traditional))
n. - 行為, 習性, 舉止

idioms:

• behavioural therapy    行動治療

한국어 (Korean)
n. - 행동, 반응

日本語 (Japanese)
n. - 振る舞い, 行動, 習性, 運転, 動き, 性質, 反応

العربيه (Arabic)
‏(الاسم) سلوك, سيرة‏

עברית (Hebrew)
n. - ‮התנהגות‬

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