Especially directed consequence of action, as considered in terms of the acts of organisms.

So defined behavior would be limited to the action of animals, and this is a reasonable narrowing of the concept. The term behavior is not always defined that narrowly, however, and also can be applied to systems that are other than individual organisms. "

No matter how defined, though, a behavior is some kind of body-intended modification in body activity – even if this modification is avoidance of doing something – and also is something that takes place over relatively short time scales.

Just how short a timescale a behavior must be over, to still be a behavior, is an important consideration that in part can be used to distinguish between more narrow versus broader definitions of just what constitutes a behavior. E.g., is a plant growing towards the a behavior? Strictly, no, but less strictly defined perhaps yes.

Behavior is a consequence of the physiology of organisms, that is, a consequence of how organism bodies work. Behavior also contributes to physiology, giving rise to various aspects contributing to as well as reproduction.

From :

Natural selection does its best to favor the production of codes guaranteeing behavior that increases fitness. fitness. A behavior program that guarantees instantaneous correct reaction to a potential , to a potential , or to a potential will certainly give greater fitness in the Darwinian sense than a program that lacks these properties. Again, a behavior program that allows for appropriate learning and the improvement of behavior reactions by various types of gives greater likelihood of than a program that lacks these properties.

See also ultimate causation versus proximate causation.