Instinct

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For other uses, see Instinct (disambiguation).

Instinct is the inherent disposition of a living organism toward a particular behavior. Instincts are generally inherited patterns of responses or reactions to certain kinds of stimuli. In humans they are most easily observed in behaviors such as emotions, sexual drive, and other bodily functions, as these are largely biologically determined. Instinct provides a response to external stimuli, which moves an organism to action, unless overridden by intelligence, which is creative and more versatile. Since instincts take generations to adapt, an intermediate position, or basis for action, is served by memory, which provides individually stored successful reactions built upon experience. The particular actions performed may be influenced by learning, environment and natural principles. Generally, the term instinct is not used to describe an existing condition or established state.

Examples can more frequently be observed in the behavior of animals (most in the less intelligent species), which perform various activities (sometimes complex) that are not based upon prior experience, such as reproduction, and feeding among insects. Other examples include animal fighting, animal courtship behavior, internal escape functions, and building of nests.

It is debatable whether or not living beings are bound absolutely by instinct. Though instinct is what seems to come naturally or perhaps with heredity, general conditioning and environment surrounding a living being play a major role. Predominately, instinct is pre-intellectual, while intuition is trans-intellectual.

1 Overview
2 Evolution
- 2.1 The Baldwin Effect
3 Instincts in humans
4 See also
5 References
6 External links

[edit] Overview

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 stimuli may be needed to trigger a 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. 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.

[edit] Evolution

Konrad Z. Lorenz being followed by his imprinted geese

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.^{[citation needed]} They return home earlier after winter, get the best breeding grounds, encouraging more breeding by them than other birds, even further encouraging this instinct.^{[citation needed]}

[edit] 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.

[edit] Instincts in humans

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".

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 notion is present in many introductory textbooks (Sociology: An Introduction, Ian Robertson, Worth Publishers, 1989), but is still hotly debated.