Instinct the inborn complex behavior of a living organism that is not learned. Since the 1910 NY Times article (Studying Instincts of Lower Animals ; Scientists' Tests Show the Cat Has to be Taught to Attack Mice), most scientific journals consider the term outdated although it remains popular among the general public and a number of scientists. Instincts are thought to occur as fixed action patterns. These fixed action patterns are unlearned and inherited. Problems occurred when it was discovered that stimuli can be variable due to imprinting in a sensitive period. An example of this are baby ducks following a man as if it were their mother who later, when they grew up, showed interest in mating with the man. Speculated examples of instinctual fixed action patterns can be observed in the behavior of animals, which perform various activities (sometimes complex) that are believed not to be based upon prior experience, such as reproduction, and feeding among insects. For example, sea turtles hatched on a beach automatically move toward the ocean and honeybees communicate the direction of a food source by dancing, all without formal instruction. Other examples include animal fighting, animal courtship behavior, internal escape functions, and building of nests. Another term for the same concept is innate behavior. Instinctual actions - in contrast to actions based on learning which are served by memory and which provide individually stored successful reactions built upon experience - have no learning curve, they are hard-wired and ready to use without learning, but do depend on maturational processes to appear. Biological predispositions are innate biologically vectored behaviors that can be easily learned. For example in one hour a baby colt can learn to stand, walk, glide, skip, hop and run. Learning is required to fine tune the neurological wiring reflex like behavior. True reflexes can be distinguished from instincts by their seat in the nervous system; reflexes are controlled by spinal or other peripheral ganglia, but instincts are the province of the brain. It is very difficult to separate biological cause from learning effects due to epigenetics. Experience will change gene expression which in some cases can be transmitted as predisposition toward a particular behavior to one's children. The number of genes and their location can change protein production which can be effected by learning and the environment. Changing the environment will change what the gene does in future generations.( The above needs citation and references) Any event that initiates an instinctive behavior is termed a key stimulus (KS) or a releasing stimulus. 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 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. 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. The definitions of what constitutes instinct in humans beyond infancy is conjectural^{[clarification needed]}. The will to invent solutions to requirements, to present self and possessions aesthetically and to be organised economically, culturally, religiously and politically could be described as instincts to survival, which are further enhanced by learned behaviors which are not instinctive. In a situation when two instincts contradict each other, an animal may resort to a displacement activity. 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.

[edit] Evolution

Many feel that instinctive behavior could be demonstrated across much of the broad spectrum of animal life. 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.

Although, this is what Charles Darwin himself wrote,

Origin of Species by Charles Darwin. Chapter VIII. Instinct. Instincts comparable with habits, but different in their origin.

"Many instincts are so wonderful that their development will probably appear to the reader a difficulty sufficient to overthrow my whole theory. I may here premise, that I have nothing to do with the origin of the mental powers, any more than I have with that of life itself. We are concerned only with the diversities of instinct and of the other mental faculties in animals of the same class"

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. Another important aspect of imprinting is sexual selection^[1]. Young birds tend to prefer the features of the parent of the opposite sex when it come to the preferred mate. An inhibitory effect is the Westermark Effect, the tendency not to be sexually attracted to siblings, because of the close contact in a sensitive period.

The idea that no learning is required for instinctive behavior does not always apply when it concerns the behaviors themselves^[specify]. The key stimuli and the specific outcome may vary somewhat due to different inputs. The output may vary in the sense that a finch will sing naturally (instinctively), but it will sing a song similar to the songs it has picked up in a sensitive period which explains the different regional accents in the finch songs.

[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. 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. In the 1870s, Wilhelm 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. 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. During the 60's and 70's, textbooks still contained some discussion of instincts in reference to human behavior.^{[citation needed]}

[edit] 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.

Instincts in humans could also be seen in what are called instinctive reflexes. Reflexes, such as the Babinski Reflex (fanning of the toes when the foot is stroked), are seen in babies and are indicative of stages of development. These reflexes could truly be considered instinctive because they are generally free of environmental influences or conditioning. Additional human traits that have been proposed as instincts are:[sleeping Some scientists^[who?] consider that it may be instinctual in children to put everything in their mouths, because this is how they tell their immune system about the environment and the surroundings, what the immune system should adapt to. Other sociologists^[who?] 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^[who?] 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, such as "Sociology:

[edit] References