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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.


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.


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 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.


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.


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.


In studying fixed-action patterns of behavior, or FAPs, Lorenz and Tinbergen observed numerous interesting phenomena. Male stickleback fish, for example, recognize potential competitionother breeding stickleback malesby 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.


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.


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).


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.


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.


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.


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 scarceagain, 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.


Animal Behavior Resources on the Internet. Nebraska Behavioral Biology Group (Web site). <>.

Applied Ethology (Web site). <>.

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). <>.

"Growth Movements, Turgor Movements, and Circadian Rhythmics." Department of Biology, University of Hamburg (Germany) (Web site). <>.

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). <>.



Learning by association with particular stimuli. There are two varieties of conditioning: classical conditioning, which involves pairing a stimulus that elicits a specific response with one that does not until the second stimulus elicits a response like the first, and operant conditioning, which involves administering or withholding reinforcements (i.e., rewards) based on the performance of a targeted response.


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.


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.


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.


Any phenomenon (for example, an environmental change) that directly influences the activity or growth of a living organism.


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.


A response to a stimulus that acts in a particular direction, thus encouraging growth either toward or away from that stimulus.

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41. Behavior

See also 28. ATTITUDES ; 279. MOODS ; 334. PSYCHOLOGY .

aberrance, aberrancy
the condition or state of being deviant or aberrant.
1. having a tendency towards, or being in a state of abnormality.
2. something that is abnormal.
a person who is characterized as being in some way abnormal.
impulsive, rash, or irresponsible actions or attitudes, especially in the sphere of public life. adventurist, n . adventuristic, adj.
the attitudes and behavior of one who exaggerates dangers or always expects disaster. alarmist , n.
Obsolete, illogicality, unreasonableness. alogic, alogical, adj.
the taking on of masculine habits and occupations by women.
the dress and conduct suitable to a pastoral existence, usually with reference to the idealized description of pastoral life in literature. Arcadian, n., adj.
1. the state of having recently achieved wealth or position, especially by unscrupulous or unethical means.
2. behavior typical of arrivism. arriviste, n., adj.
a severe self-deprivation for ethical, religious, or intellectual ends. ascetic, n., adj.
1. a sad and gloomy individual.
2. an irritable and bad-tempered person. atrabilious, adj.
the practice of striking poses, either to mask or to express personal feelings. attitudinarian, n.
the characteristics attributed to attorneys; slyness; unscrupulousness.
an automatic or involuntary action. automatist, n.
Rare. an abnormal fear of being egotistical, of referring to oneself.
babuism, babooism
Derogatory. the practices of Hindus who had only a slight English education. From bābū, a Hindi title equivalent to Sir or Mr.
showmanship or any activity taking advantage of peoples credulity or desire for sensational entertainment, as practiced by P.T. Barnum (1810-91).
the characteristics of a bashaw, especially tyranny and imperiousness.
attitudes or behavior typical of a beatnik or one who has rejected conventions of society.
a debased brutality, the opposite of humane activity: I have lost the immortal part of myself, and what remains is bestial. (Othello). See also 364. SEX .
strangeness or grotesqueness, especially strange or unconventional behavior.
behavior typical of a blackguard, characterized by use of obscene language and by roguish actions. blackguardery, n. blackguardly, adj.
the practice of individualistic, unconventional, and relaxed conduct, of ten in an artistic context, expressing disregard for or opposition to ordinary conventions. bohemian, n., adj.
conduct characteristic of a stupid person or clown. boobyish, adj.
a braggarts usual activity; bragging. braggartist, braggart, n.
the practice of advocating or engaging in brutality. brutalitarian, adj.
the set of attributes that characterize a brute. brutish, adj.
the actions of a bully.
the characteristics associated with one who advances his career even at the expense of his pride and dignity. careerist, n.
an addiction to ceremonies or ritualism, especially in social and other nonreligious contexts. ceremonialist, n.
the study of character, especially its development and its variations. characterologist, n. characterologic, characterological, adj.
the quality of having characteristics of a fraud. charlatanic, adj.
a habit or custom; usual behavior.
foolish conceit or vanity; behavior typical of a coxcomb.
reckless or foolhardy behavior. Also called daredeviltry . daredevil, n.
Obsolete, raving or maniacal behavior, as that of a bacchanal.
proper behavior; action that is seemly and in good taste. decorous, adj.
the attitudes or behavior of one who stubbornly holds on to something, as an outdated view, untenable position, etc. die-hard, n., adj.
an admiration of or interest in the arts, often used pejoratively to designate a shallow, undisciplined, or frivolous attraction. dilettante, n., adj. dilettantish, adj.
1. an action characterized as being donkeylike; foolishness.
2. the characteristic of being like a donkey. donkeyish, adj.
idleness or indolence as a habit or regular practice.
the habit of being shabbily dressed. dowdyish, adj.
the habit of performing actions in a histrionic manner.
a pedantic adherence to logically constructed rules.
an action or behavior that deviates from the norm; unpredictability in behavior.
1. a deliberately conspicuous or exaggerated mode of behavior, intended to gain attention.
2. the abnormal practice of indecent exposure. exhibitionist, n. exhibitionistic, adj.
faineance, faineancy
laziness; the state of being idle. faineant, adj.
the quality of being a fairy or having fairylike characteristics.
swaggering boastfulness; vainglorious speech or behavior. fanfaron, n.
spiritual or intellectual dissatisfaction combined with a desire for power or material advantage. After Johann Faust (c.1480-c.1538), German scholar portrayed by Marlowe and Goethe. faustian, adj.
Rare. evil attitudes and actions.
flunkyism, flunkeyism
1. the quality or state of being a servant or toady.
2. behavior typical of flunkyism. flunky, flunkey, n.
the condition of adhering solely to set formulas. formularistic, adj.
behavior typical of an earlier time; old-fashioned or stuffy attitudes; fogyism.
the condition of having brotherly qualities. fraternalist, n. fraternalistic, adj.
the administrative duties of officials. functionary, n., adj.
the habit of using organized violence to achieve ones ends. gangster, n.
boastful or bragging behavior. Also gasconadc .
1. inclined to laughter.
2. laugh-provoking in conduct or speech.
the extremely obsequious behavior of a sycophant. gnathonic, adj.
gourmandism, gormandism
1. a strong penchant for good food; gourmetism; epicurism.
2. gluttony. gourmand, gormand, n., adj.
attitudes and actions modeled on the grandees, Iberian nobles of the highest rank.
gypsyism, gipsyism
the activities and style of living attributed to gypsies. gypsy, gipsy, n. gypsyish, gipsyish, adj.
a performance involving Harlequin or other characters of the Commedia dellArte; hence, buffoonery or clownish behavior. Also harlequinery.
the practice of retiring from society and living in solitude, based upon a variety of motives, including religious. Also called hermitry, hermitship. hermitic, hermitical, adj.
a tendency to theatrical or exaggerated action. Also histriconism. histrionics, n. histrionic, adj.
the state of being a hobo or vagrant.
a dedication to taking holidays.
lawless behavior or conduct typical of a hooligan.
horsyism, horseyism
looking or acting in some way like a horse. horsy, horsey, adj. horsily, adv.
any behavior attributed to the Hottentots, in particular, a kind of stammering or stuttering.
ill-bred, boisterous, or tomboyish behavior in a woman. hoyden, n. , hoydenish, adj.
1. pretentious behavior or attitudes.
2. imposing or deceptive behavior. humbug, humbugger, n.
humoralism, humouralism
an obsolete physiological explanation of health, disease, and behavior, asserting that the relative proportions of four elemental bodily fluids or humors (blood-sanguinity, phlegm-sluggishness, black bile-melancholy, and yellow bile-choler) determined a persons physical and mental constitution. humoral, humoural, adj.
division of patriotic loyalties, ascribed by some to foreign-born citizens in the United States.
an idiosyncrasy or personal mannerism or peculiarity.
a mannerism, action, or form of behavior peculiar to one person or group. idiosyncratic, idiosyncratical, adj.
lack of shame or modesty.
1. indecorous, improper, or unseemly behavior.
2. an indecorous thing or action.
the customs or traditions of Indians, especially American Indians. Indianist, n.
the quality of revolting against established authority. insurrectionist, n., adj. insurrectionary, adj.
a tendency to irritability and sudden fits of anger. Also called irascibleness . irascible, adj.
the quality of having traits or characteristics like those of Samuel Johnson. Johnsonian, n., adj.
juvenilism, juvenility
Often pejorative. a mode of action or thought characterized by apparent youthfulness. juvenile, n., adj.
the actions and characteristics of a landlord. landlordly, adj.
the state of being noisy, rowdy, or disorderly. larrikin, adj., n.
a tendency to unrestrained, often licentious or dissolute conduct. Also libertinage . libertine, n., adj.
the pursuit or adulation of celebrities. lionize, v.
1. an inclination to dispute or disagree with others, esp. through civil suits.
2. argumentativeness. litigious, adj.
the customs and characteristics of London and of those who reside there. Londonish, adj.
macaronism, maccaronism
a tendency to foppishness. macaroni, maccaroni, n.
behavior characteristic of a maenad or bacchante; raging or wild behavior in a woman. maenadic, adj.
1. the state or quality of being a maid, a young or unmarried woman.
2 . behavior or attitude typical of maidism.
a style of action, bearing, thought, or speech peculiar to an individual or a special group. See also 23. ART . mannerist , n. manneristic, adj.
an emphasis on scrupulous attention to the details of methods and procedures in all areas of life. martinet, n. martinetish, adj.
1. a tendency in temperament to be mawkishly sentimental and tearfully emotional.
2. a degree of drunkenness characterized by mawkish emotionalism. maudlin, adj.
behavior typical of that portrayed in a melodrama, i.e., characterized by extremes of emotion.
1. the state or quality of having a lively, fickle, volatile, or erratic attitude or charaeter.
2 . an instance of such behavior. mercurial, adj.
1. the state or quality of being a weak and ineffectual person.
2 . behavior or attitudes typical of a such a person.
an intense (and sometimes injurious) tendency to mimicry.
boastful and pretentious behavior; quackery or any actions typical of a mountebank. Also mountebankery .
behavior characteristic of a boorish person.
the principle or practice of mutual dependence as the condition of individual and social welfare. mutualist, n.
weak or insipid behavior or attitude. namby-pamby, n., adj.
a quality or trait distinctive of Negroes.
conduct characteristic of a ninny, or silly fool. ninnyish, adj.
a rootless, nondomestic, and roving lifestyle. nomadic, adj.
the practice of going nude. nudist, n., adj.
the characteristics and customs of people situated in western regions, especially the Western Hemisphere, as western European countries and the United States. Occidentalist, n.
the condition of resembling an ogre in actions and characteristics. ogreish, adj.
the conscious policy and practice of taking selfish advantage of circumstances, with little regard for principles. opportunist, n. opportunistic, adj.
the habits, qualities, and customs of Oriental peoples. Orientalist, Orientality, n.
mindless imitation. Also called parrotry .
the adherence to an exclusive subject, interest, or topic. particularist, n. particularistic, adj.
1. behavior or attitudes typical of one who has recently acquired wealth or social position.
2 . the state or quality of being a parvenu or upstart. parvenu, n., adj.
1 . the state of being a member of one of the original citizen families of ancient Rome.
2 . the state of being noble or high born. patriciate, n.
the quality of having common manners, character, or style. plebeian, n., adj.
a tendency to conduct expressing indifference, nonchalance, or lack of concern. pococurante, pococurantist, n. pococurante, adj.
the characteristics associated with being a coward or wretch. Also called poltroonery . poltroonish, adj.
a penchant for meddlesomeness and officiousness. Also polypragmacy, polypragmaty . polypragmatist, n. polypragmatic, adj.
one whose conduct is unchaste, licentious, or lewd.
praxeology, praxiology
the study of human behavior and conduct. praxeological, adj.
excessive fastidiousness or over-refinement in language or behavior.
hasty or rash action, behavior, etc.; undue or ill-considered haste. precipitant, adj.
the strict adherence to correctness of behavior. prigger, n. priggish, adj.
1 . dissolute or immoral behavior.
2. reckless and extravagant spending or behavior. profligate , adj.
the actions and qualities of a protagonist. protagonist , n.
a tendency to peevish, petulant, or insolent conduct.
psychagogics, psychagogy
a method of affecting behavior by assisting in the choice of desirable life goals. psychagogue , n.
affected or impertinent behavior; conceit.
a tendency to absurdly chivalric, visionary, or romantically impractical conduct. quixotic, quixotical, adj.
Rare. a tendency to railing and quibbling. rabulistic, rabulous, adj.
the condition of being reactionary or resistant to change. reactionist , n., adj.
the characteristics of a reporter.
the qualities of a reunion or social gathering. reunionist , n.
the state of being revolutionary. revolutionary, revolutionist, n. revolutional, revolutionary, adj.
the excessive adherence to a routine. routinist , n.
noisy, quarrelsome, or disorderly conduct or behavior. rowdy , n., adj.
behavior typical or characteristic of a brutal and violent person. ruffian , n.
diabolical behavior. Satanist , n.
the condition of having uncivilized or primitive qualities. savagedom , n.
the practices characteristic of a schoolboy. schoolboyish , adj.
the characteristics and behavior of a scoundrel. scoundrelly , adj.
a person who seeks solitude or removes himself from the society of others; a recluse.
the quality of having sensation. sensorial . adj.
Archaic. an ecstatic devotion, especially religious.
1 . a person who delivers sermons.
2 . a person who adopts a preaching attitude.
a tendency to whimsical conduct in accord with absurd theories from past ages. [Allusion to the actions of Walter, father of the hero in Sternes Tristram Shandy. ]
a tendency to conduct marked by outbursts of strong emotion. spasmodist , n. spasmodic, spasmodical, adj.
activity characteristic of the observance of Sunday as a holy day.
the condition of having qualities or traits like those of a superman. supermanly , adj.
a love of luxury. [Allusion to Sybaris, a Greek colony in Italy not-ed for its luxury.] sybarite, n. sybaritic , adj.
the practice of self-serving or servile flattery. Also called sycophancy . sycophant , n. sycophantic , adj.
the condition of having coinciding emotions in two or more people.
Obsolete. a form of teasing or harassment in which a hope of some good or benefit is instilled in the victim, only to be repeatedly dashed and the reward shown to be unattainable.
hypocrisy. [Allusion to Molières hypocritical hero, Tartuffe.] Also called tartuffery.
a tendency to actions marked by exaggerations in speech or behavior. Also called theatricism.
the habit of extreme neatness.
a personal despair leading to misanthropy. [Allusion to Shake-speares Timon of Athens. ]
a fawning flattery, obsequiousness, or sycophancy. toady , n. toadyish , adj,
formal or superficial compliance with a law, requirement, convention, etc.
the conduct characteristic of a tomboy, a boyish girl. tomboyish , adj.
Turcism, Turkism
Obsolete, the attitudes and actions of the Turks.
the habit of giving opinions and advice on matters outside of ones knowledge or competence. ultracrepidarian , n., adj.
1 . the tendency to wander from place to place without a settled home; nomadism.
2 . the life of a tramp; vagrancy. Also called vagabondage. vagabond , n., adj.
the malicious destruction or defamation of public or private property. vandal, vandalization, n. vandalish , adj.
the actions or thoughts of members of a vanguard, those at the forefront of a movement, fad, etc. vanguardist , n.
the affection for or emulation of Victorian tastes or thoughts.
the actions characteristic of a Viking, i.e., savagery, rapaciousness, etc.
the compulsion to seek sexual gratification by secretively looking at sexual objects or acts; the actions of a Peeping Tom. voyeur , n. voyeuristic , adj.
Rare. the state or quality of being foxlike, especially crafty or cunning. vulpine , adj.
behavior or character typical of a vulture, especially in the figurative sense of being rapacious. vulturous , adj.
the quality of having the traits of a werewolf.
a penchant for rowdyism. [Allusion to Swifts characters in Gullivers Travels. ]
1 . the state or quality of being a yokel or country bumpkin.
2 . behavior, language, etc, typical of a yokel.
the style of a zany or buffoon.
zealotism, zealotry
a tendency to undue or excessive zeal; fanaticism.
1. abnormal zeal.
2 . morbid jealousy. zelotypic , adj.

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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 oxymoronthat 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 markersstretches 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 distractibleand those who were less cautious, less fearful, less shy, and less inhibitedhave 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 181/2. 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 181/2. 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 181/2, 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.

Richard J. Rose

and Danielle M. Dick


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.

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Animal behavior includes the actions and reactions of animals to external stimuli. The study of animal behavior involves two main approaches: answering questions about how an animal does something (proximate questions) and why an animal does something (ultimate questions). Though humans have always observed animals behave, animal behavior did not become a field of study until the 1930s, when it was called ethology .

Behavior is determined by both genetics and environmental factors, and is controlled by neural mechanisms. Thus, all animals with nervous systems are capable of behavior, including extremely simple ones such as the flatworm, Caenorhabditis elegans, which responds to light. The study of animal behavior is expanding rapidly and includes taxa and subjects too numerous to list here. Major divisions of the field include learning, cognition, and social behavior.

Founders of animal behavior studies include scientists Karl von Frisch, Konrad Lorenz, and Niko Tinbergen, whose work in the 1930s won them a shared Nobel Prize in 1973. Their work focused on how animals can do things they have never before seen done, which is a proximate question relating to the genetics that determine some of an animal's makeup and the physiology that allows the animal to perform the feat.

Their work also included elements of ultimate questions, and it is the answers to these "why" questions that lead us to fully understand the driving force behind the evolution of the behavior. Using the C. elegans example given above, questions about how the flatworm avoids light will be answered by geneticists and physiologists studying light sensors and locomotion capabilities. Why the flatworm avoids light relates to things like evolution (its ancestors avoided light, and it increases an individual's fitness for survival to do so) and environment (predators can detect flatworms better in the light). These ultimate questions helped link the fairly new study of behavior to established disciplines of evolution and ecology , and gave birth to the field we know today as behavioral ecology.

Behavior is a phenotypic trait , and, as with other such traits, an individual's behavior is determined through both genetics and environment. There are few examples of a trait that is strictly determined through just one of these routes, though through rigorous study we can tease apart the genetic and environmental components that determine a behavior.

For example, when a gene for a complex behavior such as alcoholism is reported, it usually means that there has been an abnormal allele of a gene found in some large percentage of alcoholics tested, and that the presence of this allele may somehow make the individuals with it more likely to be alcoholics. It does not indicate, however, that all people with that allele are alcoholics or that all alcoholics have that allele. There are many social factors such as depression and stress that contribute to alcoholism.

Behavior is controlled by the nervous system. Nerve cells acquire sensory cues from the environment, such as light in the case of C. elegans, and convert them to electrical signals that are transported to a central decision-making location, such as a nerve ganglion in C. elegans or the brain in a higher animal. There it will be determined whether the received stimulus demands a reaction. From there, another electrical signal will be sent back out to the target where the response will occur, such as a muscle that controls locomotion and performs the actual behavior.


One loosely defined category of animal behavior is learning, and this includes imprinting, kin recognition, associative learning, and play. During learning, behaviors are changed based on what an individual sees or experiences.

Imprinting is irreversible learning that occurs during a specific time in an individual's development. Documented in both mammals and birds, one type of imprinting is the recognition and bond that develops between the parent and child in the first few days after birth. A famous example of this occurred when Konrad Lorenz divided a clutch of goose eggs in half, and allowed half of them to incubate with their mother and the other half in an incubation chamber. Those in the first half displayed normal behavior, following their mother around and ultimately interacting and mating with other geese. Those in the second half spent their first few hours with Lorenz and the baby geese imprinted on him. Even when these geese were later reintroduced to their mother and siblings, they showed no recognition but instead always followed Lorenz around and even later showed courtship behavior toward humans. This experiment shows the importance of the critical period in which imprinting occurs (the first few hours of life in this case) and the irreversibility of what is learned, even when the species that is imprinted (a human in this case) is incorrect.

Another example of imprinting includes recognition of kin. At an early age, odors of the nest and early companions are used as cues that let animals recognize who their kin are. Documented even in insects, this kin recognition can be used to explain interactions later in life (significantly after separation from the nest) in which an animal treats another one like a relative if it smells like the nest from which it originated. This may be an important part of kin selection, which is discussed in the final, social behavior paragraph of this entry.

Other types of learning, such as associative learning, are not dependent on a critical period, though the learning may happen most efficiently if taught at a certain time. Associative learning is simply the ability to associate one stimulus with another. One example is trial-and-error learning, where as a result of a certain behavior and its outcome, a good or bad association is learned. Whether an association is positive or negative ultimately leads to the repetition or avoidance of the behavior. Food choices may fall under this category, where the sampling of different food types may lead to satisfaction and nourishment or bad taste and sickness.

Finally, play can be viewed as a type of learning in which capturing prey and social behavior are practiced. Though play is usually done with siblings and without the actual goals of hunting to kill or establishing social and mating hierarchies, the actions practiced in play allow these skills to be practiced for use later on.

Cognitive Behaviors

A second group of behaviors that can be loosely gathered together are cognitive behaviors. These are complex behaviors that involve the perception, storing, processing, and use of information.

Long-distance travel is an example of this complex process. Whales, butterflies, and birds travel thousands of kilometers to return to the exact same spot they were the year before. Migrating animals use several mechanisms including orientation, piloting, and navigation. Orientation involves moving in a certain compass direction, which can be known from cues like stars and the Sun, although some animals can detect magnetic north without these cues.

Piloting is employed for short distances. It involves moving between landmarks such as rivers and mountains that are familiar from past migrations.

Navigation is the most complex. It involves both determining present location in relation to other known locations and using orientation to get to the next destination. This means the animal must create a mental map that is spatially correct in order to plot out the next course.

Social Behaviors

A third group of behaviors is related to social living. Examples include communication, cooperation, and competition. Communication can be between species, such as when a dog snarls to expose its teeth to warn a potential attacker what may be in store. Frequently, communication occurs among species and can be aural such as bird song or cricket chirp; olfactory , such as a spot where an animal urinates; visual; or tactile .

Communication serves a myriad of purposes, including defining territories, attracting mates, telling where a food source is, or warning of impending danger. Cooperation is when two or more individuals work to perform a single task. Many times this task may seem more beneficial to one individual than the other, in which case the individual getting less or no benefit is termed altruistic. Examples of cooperation are in food finding, child rearing, and standing watch for predators.

In many cases of apparent altruism, it is found that the individual receiving the benefit is related to the one giving, such that the one giving is actually helping to preserve a genetically related line. This phenomenon is called kin selection and serves to propagate related genomes , an act that is not purely altruistic.

Competition occurs when a limited resource needs to be divided among individuals. An example of a resource to be divided is territory. Frequently, males must establish a territory that has good food or is a good mating or nesting spot so that they are preferentially chosen by females for mating. Those males who accomplish this are the most successful in passing on their genes. Competition for territory can take the form of violent contests with other males, and even after the territory is won it may need vigilant guarding to keep intruders out.

see also Acoustic Signals; Behavioral Ecology; Communication; Courtship; Social Animals; Sociobiology.

Jean K. Krejca


Alcock, John. Animal Behavior, 6th ed. Sunderland, MA: Sinauer Associates, 1998.

Campbell, Neil A., Jane B. Reece, and Lawrence G. Mitchell. Biology, 5th ed. Menlo Park, CA: Benjamin Cummings, 1999.

Halliday, Tim. Animal Behavior. Norman: University of Oklahoma Press, 1994.

Lorenz, Konrad. King Solomon's Ring. New York: Harper & Row, 1952.

Maier, Richard A., and Barbara M. Maier. Comparative Animal Behavior. Belmont, CA: Brooks/Cole Publishing, 1970.

Mellgren, Roger L., ed. Animal Cognition and Behavior. New York: North-Holland Publishing Company, 1983.

Wilson, Edward O. Sociobiology: The New Synthesis. Cambridge, MA: The Belknap Press of Harvard University Press, 1975.

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Behavior is the way that all organisms or living things respond to stimuli in their environment. Stimuli include chemicals, heat, light, touch, and gravity. For example, plants respond with growth behavior when light strikes their leaves. Behavior can be categorized as either instinctive (present in a living thing from birth) or learned (resulting from experience). The distinction between the two is often unclear, however, since learned behavior often includes instinctive elements. Plants and animals that lack a well-developed nervous system rely on instinctive behavior. Higherdeveloped animals use both instinctive and learned behavior. Generally, behavior helps organisms survive.

Plant behavior

The instinctive behavior of a plant depends mainly on growth or movement in a given direction due to changes in its environment. The growth or movement of a plant toward or away from an external stimulus is known as tropism. Positive tropism is growth toward a stimulus, while negative tropism is growth away from a stimulus. Tropisms are labeled according to the stimulus involved, such as phototropism (light) and gravitropism (gravity). Plants growing toward the direction of light exhibit positive phototropism. Since roots grow downward (with gravity),

Words to Know

Ethology: The scientific study of animal behavior under natural conditions.

Operant conditioning: Trial-and-error learning in which a random behavior is rewarded and subsequently retained.

Stimulus: Something that causes a behavioral response.

Tropism: The growth or movement of a plant toward or away from a stimulus.

they exhibit positive gravitropism. Stems of plants grow upward (against gravity), exhibiting negative gravitropism.

Animal behavior

The scientific study of animal behavior under natural conditions, known as ethology, focuses on both instinctual and learned behavior. Ethologists look at an animal's environment to see how events in that environment combine with an animal's instincts to shape overall behavior. This is especially important in the developing or early stages of an animal's life.

Animals exhibit various levels of instinctual behavior. On a elementary level are reflexes. A reflex is a simple, inborn, automatic response of a part of the body to a stimulus. Reflexes help animals respond quickly to a stimulus, thus protecting them from harm. Other instinctual behaviors are more complex. Examples of this kind include the nest-building behavior of birds and the dam-building behavior of beavers.

Imprinting. An example of animal behavior that combines instinct and learning is imprinting, often seen in birds such as geese and ducks. Within a short, genetically set time frame an animal learns to recognize and then bond to its parent, helping it to survive its infancy. Newly hatched geese or goslings are able to walk at birth. They quickly learn to recognize the movements of their parents and then follow them. If the parents are removed within the first few days after birth and are replaced by

any moving object, the goslings imprint or bond to that object, learning to follow it.

Animals often add to their set of instinctual behaviors through trial-and-error learning, known as operant conditioning. Young chimps, for example, watch their parents strip a twig and then use the prepared stick to pick up termites from rotten logs. When the young chimps repeat this procedure, their behavior is rewarded by the meal of termites, a preferred food. This reward teaches the chimps to repeat the same behavior when next hungry.

Courtship behaviors. There are many kinds of interactive behavior between animals. One of them is courtship behavior, which enables an animal to find, identify, attract, and arouse a mate. During courtship, animals use rituals, a series of behaviors performed the same way by all the males or females in a species. These include leaping and dancing, singing, the ruffling of feathers, or the puffing up of pouches. The male peacock displays his glorious plumage to the female. Humpback whales announce their presence under the sea by singing a song that can be heard hundreds of miles away.

Group behaviors. Some animals live together in groups and display social behavior. The group protects its members from predators, and allows cooperation and division of labor. Insects, such as bees, ants, and termites, live in complex groups in which some members find food, some defend the colony, and some tend to the offspring. Hierarchies or ranking systems help reduce fighting in a group. Chickens, for example, have a peck-order from the dominant to the most submissive. Each chicken knows its place in the peck-order and does not challenge chickens of higher rank, thereby reducing the chances of fighting. Interactions among group members get more complex with more intelligent species such as apes.

[See also Brain; Nervous system ]

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"Behavior." UXL Encyclopedia of Science. . 15 Dec. 2017 <>.

"Behavior." UXL Encyclopedia of Science. . (December 15, 2017).

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be·hav·ior / biˈhāvyər/ (Brit. be·hav·iour) • n. the way in which one acts or conducts oneself, esp. toward others: good behavior his insulting behavior toward me. ∎  the way in which an animal or person acts in response to a particular situation or stimulus: the feeding behavior of predators. ∎  the way in which a natural phenomenon or a machine works or functions: the erratic behavior of the old car. PHRASES: be on one's best behavior behave well when being observed: warn them to be on their best behavior.

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"behavior." The Oxford Pocket Dictionary of Current English. . 15 Dec. 2017 <>.

"behavior." The Oxford Pocket Dictionary of Current English. . (December 15, 2017).

"behavior." The Oxford Pocket Dictionary of Current English. . Retrieved December 15, 2017 from


behavior, in biology: see ethology.

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"behavior." The Columbia Encyclopedia, 6th ed.. . 15 Dec. 2017 <>.

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behavior •Antakya •Britannia, lasagne •Katya • Vanya •Kenya, Mantegna, Sardegna, tenure •failure • Montagna •behaviour (US behavior), misbehaviour (US misbehavior), saviour (US savior) •seguidilla, tortilla •Monsignor •Melanesia, Micronesia, Polynesia •Tigrinya • De Falla • Vaisya •Lockyer • Bologna • sawyer • bowyer •alleluia, hallelujah •La Coruña •bunya, gunyah

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"behavior." Oxford Dictionary of Rhymes. . 15 Dec. 2017 <>.

"behavior." Oxford Dictionary of Rhymes. . (December 15, 2017).

"behavior." Oxford Dictionary of Rhymes. . Retrieved December 15, 2017 from