Why do swallows fly south in winter? Why do salmon return to their natal stream for reproduction and what is the reason a baby turtle makes its way to the open ocean? It is all due to instinct. Instinct is an inborn pattern that is characteristic of a species and is often a response to specific environmental stimuli.
Any behavior is instinctive if it is performed without being based upon prior experience and is therefore an expression of inborn biological factors. Like when a baby kangaroo climbs into its mother’s pouch upon being born. Or when honeybees communicate by dancing in the direction of a food source. Another example of instinctive behavior is bird migration. Migrating birds navigate using celestial cues from the sun and stars, the earth’s magnetic field, and probably also mental maps.
An event that triggers a behavior is called a key stimulus. When looking at bird migration, the timing of migration seems to be controlled primarily by changes in day length. In this case the key stimulus is the fact that it gets dark earlier. Key stimuli produce fixed action patterns. Sensory receptor cells are important for receiving different types of stimuli. The neural networks of these different sensory cells help to determine the degree of the stimulus and thereby produce an appropriate response. Many of these responses are controlled by the endocrine system, which is responsible for the production and transportation of hormones.
When looking at instinct, it is important to distinguish the difference between reflexes and instinctive behavior. A reflex is an involuntary and instantaneous movement in response to a stimulus. Reflexes are usually reasonably simple behaviors that don’t last long, such as the contraction of the pupil in response to bright light. The stimulus in a reflex does not require brain activity but instead travels to the spinal cord as a message that is then transmitted back through the body, tracing a path called the reflex arc. Instinctive behavior does require brain activity and are usually more complex behaviors that last longer periods of time.
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. Most of the information processing in the brain takes place in the cerebral cortex. Specific areas of the cerebral cortex are involved in vision, hearing, touch, movement and smell. Other areas are critical for thinking, reasoning and social learning. For species that have a more developed cerebral cortex, like elephants, instincts play a lesser role than for a frog for example. Lionesses and chimpanzees raised in zoos away from their birth mothers often reject their own offspring because they have not been taught the skills of mothering. Therefore, nurturing is not completely an instinctive behavior but a type of behavior that is taught to offspring by their parent(s). Such is not the case with simpler species such as reptiles, where this mothering behavior is mostly due to instinct.
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 siblings were flying. These birds flew immediately and normally when released, showing that their improvement resulted from instinct and not learning behavior.
Humans also portray instinctive behavior. A 2012 study published in the journal Proceedings of the National Academy of Sciences, demonstrated that humans have an amazing ability to integrate value when they do so intuitively. The human brain most likely has a system on which decision making is based. This system has the capacity to take in pieces of information and decide on an overall value which, in this study, turned out to be the right call up to 90 percent of the time. Remember, it’s the voice that doesn’t use words you should listen to.