Ethology (II)
Two approaches can be used to study animal instincts: the first, to determine the adaptive significance of the instinct, that is to say, how it contributes to ensure the survival of the animal or its offspring. The second approach is to determine which are the genetic mechanisms involved in the production of a given behavior. Both approaches have originated new sciences. Sociobiology is the science that studies animal and human behavior from an evolutionary point of view. Behavioral genetics, on the other hand, is the science that studies the influence of genes in instinctive behavior and the underlying physiological mechanisms.
As a result of work in the genetic field, some scientists now consider that in addition to instinctive and learned behaviors there exist intermediate kinds of behaviors that are partly learned and partly instinctive. One example is the bird species whose members do not learn the species song if they are raised in isolation, or if they hear the song after the first year of life. If they are raised with other birds, they do not learn the other birds' song either.
Therefore, instincts have been classified into 'closed instincts,' those that are produced in full form since the first time, and 'open instincts,' those that can be modified, or need to be completed, by learning. An example of the latter class of instinct--also called restricted learning--is the classic example of 'imprinting.' Newly hatched ducklings follow any moving object near them, normally their mother. It is supposed that during this following the young learn the characteristics of the species' female.
In addition to the evolutionary significance of behavior, ethologists also explore the relation between environment and behavior. To do this, they observe different species that live in the same environment. When the same behavior is detected, a conclusion is made that it is produced by the environment's influence.
According to the law of natural selection, a variation is selected when it enhances the odds of surviving of the animal, thus permitting it to have more descendants. A behavior can be considered adaptive when it has a positive effect in reproductive success. For example, selection of a place to live, strategies to avoid predators and to find food, can be considered adaptive behaviors. Territoriality, the behavior by which an animal defends a territory where it can reproduce and feed, can also be considered within this category.
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