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Instinct is the inherent disposition of a living organism toward a particular behavior. Animal instinctive behavior is an aspect of animal ethologywhich recognises at least seven instincts. These are for:
Instincts are unlearned, inherited fixed action patterns of responses or reactions to certain kinds of stimuli. Innate emotions, which can be expressed in more flexible ways and learned patterns of responses, not instincts, form a basis for majority of responses to external stimuli in evolutionary higher species, while in case of highest evolved species both of them are overridden by actions based on cognitive processes with more or less intelligence and creativity, or even trans-intellectual intuition.
Whether a particular behavior pattern is inherited or learned is not always easy to determine, because some inherited behaviors may be modified by experience.
The simplest example of an instinctive behavior is a fixed action pattern, in which a very short to medium length sequence of actions, without variation, are carried out in response to a clearly defined stimulus.
Any behavior is instinctive if it is performed without being based upon prior experience (that is, in the absence of learning), and is therefore an expression of innate biological factors. Sea turtles, newly hatched on a beach, will automatically move toward the ocean. A joey climbs into its mother's pouch upon being born. Honeybees communicate by dancing in the direction of a food source without formal instruction. Other examples include animal fighting, animal courtship behavior, internal escape functions, and the building of nests. All of these are examples of complex behaviors and are thus substantially different from simple reflex behaviors.
An instinct should be distinguished from a reflex, which is a simple response of an organism to a specific stimulus, such as the contraction of the pupil in response to bright light or the spasmodic movement of the lower leg when the knee is tapped. Instincts, in contrast, are inborn complex patterns of behavior that must exist in every member of the species and that cannot be overcome by force of will.  However, the absence of volitional capacity must not be confused with an inability to modify fixed action patterns. For example, people may be able to modify a stimulated fixed action pattern by consciously recognizing the point of its activation and simply stop doing it, whereas animals without a sufficiently strong volitional capacity may not be able to disengage from their fixed action patterns, once activated. 
Commonly cited examples of presumed instincts in humans are the "maternal instinct" and the "survival instinct". These examples however do not conform to the scientific definition of instinct. Many human females do not desire children and furthermore some mothers kill their own children. Similarly, many humans contradict their own survival through suicide.
The role of instincts in determining the behavior of animals varies from species to species. The more complex the neural system of an animal, the greater is the role of the cerebral cortex, and social learning and instincts play a lesser role. A comparison between a crocodile and an elephant illustrates how mammals for example are heavily dependent on social learning. Lionesses and chimpanzees raised in zoos away from their birth mothers most often reject their own offspring because they have not been taught the skills of mothering. Such is not the case with simpler species such as reptiles.
Examples of instinctual fixed action patterns can be observed in the behavior of animals, which perform various activities (sometimes complex) that are not based upon prior experience and do not depend on emotion or learning, such as reproduction, and feeding among insects. Other areas in which behavior may be largely instinctive include:
- Animal aggressive behavior
- Animal courtship behavior
- Animal defensive behavior
- Animal distress calls
- Animal exploratory behavior
- Animal homing
- Animal motivation
- Animal parental behavior
- Animal predatory behavior
- Animal sexual behavior
- Attack behavior
- Species recognition
- Nest building
- Animal hoarding behavior
- Avian incubation
- Freezing behavior
Instinctual actions - in contrast to actions based on learning which is served by memory and which provides individually stored successful reactions built upon experience - have no learning curve, they are physiologically hard-wired, presumbly genetic in origin and ready to use without learning, but do depend on maturational processes to appear.
Technically speaking, any event that initiates an instinctive behavior is termed a key stimulus (KS). Key stimuli in turn lead to innate releasing mechanisms (IRM), which in turn produce fixed action patterns (FAP). More than one key stimulus may be needed to trigger an FAP. Sensory receptor cells are critical in determining the type of FAP which is initiated. For instance, the reception of pheromones through nasal sensory receptor cells may trigger a sexual response, while the reception of a "frightening sound" through auditory sensory receptor cells may trigger a fight or flight response. The neural networks of these different sensory cells assist in integrating the signal from many receptors to determine the degree of the KS and therefore produce an appropriate degree of response. Several of these responses are determined by carefully regulated chemical messengers called hormones. The endocrine system, which is responsible for the production and transport of hormones throughout the body, is made up of many secretory glands that produce hormones and release them for transport to target organs. Specifically in vertebrates, neural control of this system is funneled through the hypothalamus to the anterior and posterior pituitary gland. Whether or not the behavioral response to a given key stimuli is either learned, genetic, or both is the center of study in the field of behavioural genetics. Researchers use techniques such as inbreeding and knockout studies to separate learning and environment from genetic determination of behavioral traits. And humans as a matter of speaking have no instincts past the early stages of infancy[How to reference and link to summary or text]. Instinct should not be confused with responses that an organism is born with such as breathing, hunger, sex drive etc. These are no different than sight, aural ability, tactility or taste perception[How to reference and link to summary or text].
In a situation when two instincts contradict each other, an animal may resort to a displacement activity.
Reflexes and instinct
Examples of behaviors that do not require conscious will include many reflexes. The stimulus in a reflex may not require brain activity but instead may travel to the spinal cord as a message that is then transmitted back through the body, tracing a path called the reflex arc. Reflexes are similar to fixed action patterns in that most reflexes meet the criteria of a FAP. However, a fixed action pattern can be processed in the brain as well; a male stickleback's instinctive aggression towards anything red during his mating season is such an example. Examples of instinctive behaviors in humans include many of the primitive reflexes, such as rooting and suckling, behaviors which are present in mammals.
Some instinctive behaviors depend on maturational processes to appear. For instance, we commonly refer to birds "learning" to fly. However, young birds have been experimentally reared in devices that prevent them from moving their wings until they reached the age at which their cohorts were flying. These birds flew immediately and normally when released, showing that their improvement resulted from neuromuscular maturation and not true learning.
Instinctive behavior can be demonstrated across much of the broad spectrum of animal life, down to bacteria that propel themselves toward beneficial substances, and away from repellent substances. According to Darwin's theory of evolution by natural selection, a favorable trait, such as an instinct, will be selected for through competition and improved survival rate of life forms possessing the instinct. Thus, for evolutionary biology, instincts can be explained in terms of behaviors that favor survival.
A good example of an immediate instinct for certain types of bird is imprinting. This is the behaviour that causes geese to follow around the first moving object that they encounter, as it tends to be their mother. Much work was done on this concept by the psychologist Konrad Lorenz. Evolution however encourages multiple instincts, exampled by the recent case of birds in England flying east for the winter, the result being that because of global warming these birds are now surviving at very high rates, further encouraging this behavior.[How to reference and link to summary or text] They return home earlier after winter, get the best breeding grounds, encouraging more breeding by them than other birds, even further encouraging this instinct.[How to reference and link to summary or text]
The Baldwin Effect
In 1896, James Mark Baldwin offered up "a new factor in evolution" through which acquired characteristics could be indirectly inherited. This "new factor" was termed phenotypic plasticity: the ability of an organism to adjust to its environment during the course of its lifetime. An ability to learn is the most obvious example of phenotypic plasticity, though other examples are the ability to tan with exposure to the sun, to form a callus with exposure to abrasion, or to increase muscle strength with exercise. In addition, Baldwin pointed out that, among other things, the new factor could explain punctuated equilibria. Over time, this theory became known as the Baldwin effect.
The Baldwin effect functions in two steps. First, phenotypic plasticity allows an individual to adjust to a partially successful mutation, which might otherwise be utterly useless to the individual. If this mutation adds to inclusive fitness, it will succeed and proliferate in the population. Phenotypic plasticity is typically very costly for an individual; learning requires time and energy, and on occasion involves dangerous mistakes. Therefore there is a second step: provided enough time, evolution may find an inexorable mechanism to replace the plastic mechanism. Thus a behavior that was once learned (the first step) may in time become instinctive (the second step). At first glance, this looks identical to Lamarckian evolution, but there is no direct alteration of the genotype, based on the experience of the phenotype.
The term "instincts" has had a long and varied use in psychology. In the 1870's, W. Wundt established the first psychology laboratory. At that time, psychology was primarily a branch of philosophy, but behavior became increasingly examined within the framework of the scientific method. This method has come to dominate all branches of science. While use of the scientific method led to increasingly rigorous definition of terms, by the close of the 19th century most repeated behavior was considered instinctual. In a survey of the literature at that time, one researcher chronicled 4000 human instincts, meaning someone applied the label to any behavior that was repetitive. As research became more rigorous and terms better defined, instinct as an explanation for human behavior became less common. In a conference in 1960, chaired by Frank Beach, a pioneer in comparative psychology and attended by luminaries in the field, the term was restricted in its application. During the 60's and 70's, textbooks still contained some discussion of instincts in reference to human behavior. By the year 2000, a survey of the 12 best selling textbooks in Introductory Psychology revealed only one reference to instincts, and that was in regard to Freud's referral to the "id instincts."
Any repeated behavior can be called "instinctual." As can any behavior for which there is a strong innate component. However, to distinguish behavior beyond the control of the organism from behavior that has a repetitive component we can turn to the book Instinct (1961) stemming from the 1960 conference. A number of criteria were established which distinguishes instinctual from other kinds of behavior. To be considered instinctual a behavior must a) be automatic, b) be irresistible, c) occur at some point in development, d) be triggered by some event in the environment, e) occur in every member of the species, f) be unmodifiable, and g) govern behavior for which the organism needs no training (although the organism may profit from experience and to that degree the behavior is modifiable). The absence of one or more of these criteria indicates that the behavior is not fully instinctual.
If these criteria are used in a rigorous scientific manner, application of the term "instinct" cannot be used in reference to human behavior. When terms, such as mothering, territoriality, eating, mating, and so on, are used to denote human behavior they are seen to not meet the criteria listed above. In comparison to animal behavior such as hibernation, migration, nest building, mating and so on that are clearly instinctual, no human behavior meets the necessary criteria. In other words, under this definition, there are no human instincts.
Some sociobiologists and ethologists have attempted to comprehend human and animal social behavior in terms of instincts. Psychoanalysts have stated that instinct refers to human motivational forces (such as sex and aggression), sometimes represented as life instinct and death instinct. This use of the term motivational forces has mainly been replaced by the term instinctual drives.
Instincts in humans can also be seen in what are called instinctive reflexes. Reflexes, such as the Babinski Reflex (fanning of the toes when foot is stroked), are seen in babies and are indicative of stages of development. These reflexes can truly be considered instinctive because they are generally free of environmental influences or conditioning.
Additional human traits that have been looked at as instincts are: altruism, disgust, face perception, language acquisitions, "fight or flight" and "subjugate or be subjugated". Some experiments in human and primate societies have also come to the conclusion that a sense of fairness could be considered instinctual, with humans and apes willing to harm their own interests in protesting unfair treatment of self or others.
Other sociologists argue that humans have no instincts, defining them as a "complex pattern of behavior present in every specimen of a particular species, that is innate, and that cannot be overridden." Said sociologists argue that drives such as sex and hunger cannot be considered instincts, as they can be overridden. This definitory argument is present in many introductory sociology and biology textbooks, but is still hotly debated.
- Animal physiological psychology
- Behavioral genetics
- Biological Imperative
- Central pattern generators
- Drive theory
- Human nature
- Nature nurture
- Nervous system
- Physiological psychology
- Psychological nativism
- Self preservation
- Spontaneous alternation
- YouTube video of joey climbing into its mother's pouch.
- Naiman, Joanne. (2004) How Societies Work. Thomson Publishers. 3rd ed.
- Lorenz, Konrad. "Behind the Mirror, A Search for a Natural History of Human Knowledge", (1973) R. Piper & Co. Verlag, English translation (1977) Methuen & Co.
- Campbell and Reece, 6th ed.
- Sociology: An Introduction - Robertson, Ian; Worth Publishers, 1989
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