Defining Behavior

Simply defined, behavior is organized, goal-oriented movement on the part of an organism. Even plants "behave" in a simple sense, and the study of "animal" behavior normally extends beyond the bounds of the animal kingdom to include the behavior of bacteria and protists. Usually there is an internal system--the nervous system or something analogous to it--which organizes and initiates behavior. To achieve movements, there must be effectors--contractile elements, cilia, flagellae, or muscles. Behavior is the tool organisms have to get around in the environment, to find suitable resources, to mate, and to coordinate activities in groups of organisms.

The study of behavior, though, extends beyond looking at just the outward physical manifestation (movement). Proximate forces (meaning things that act within an animal's lifetime) all play roles in shaping an animal's behavior. Learning, the storage of information, is in the domain of animal behaviorists, as are the neurobiological, endocrinological, and physiological factors that regulate behavior.

Ultimate (evolutionary) forces also shape animal behavior. Evolution favors morphological mutations which allow animals to perform their behaviors better . In other words, morphological innovation doesn't arise in response to a need, but if, by chance, it does arise, animals carrying the genes for the new morphology will be more likely to have progeny, due to natural selection. The same logic applies to internal features, such as regulatory physiology and brain structure. Thus animal behaviorists often test evolutionary hypotheses, or use evolutionary thinking in interpreting behavior. Animal behavior is a broad field, incorporating many aspects of animal life.

A major pitfall in the study of behavior is uncritical adaptationist thinking (Gould and Lewontin 1979). There's a temptation, when a behavior is observed, to conjecture about the adaptative value of the behavior. The appropriate approach is to formulate hypotheses for the function of the behavior, and to test the hypotheses in a careful, controlled manner. Constructing "just so stories" about behavior should be avoided (Kipling 1907). On the other hand, there is a reasonable expectation that with appropriate testing, much of animal behavior is adaptive, and completely abandoning a search for adaptive explanations for behavior may cause you to ignore important underpinnings of behavior.

Some behavior, though, is clearly maladaptive. The assumption that all of an animal's behavior is in its own, best, self-interest is clearly false. Examples of behavior that is, or may be, maladaptive include aggressive behavior towards inappropriate targets, behavior when a parasite exerts behavioral control over its host, and sexual behavior targeted at an inapropriate individual, such as a member of another species. We need to be willing to accept that not all behavior has an adaptive explanation, and that, indeed, some behavior can be pathological or maladaptive.

Gould S J, Lewontin R C 1979 Spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist program. Proceedings Of The Royal Society Of London Series B-Biological Sciences 205 (1161): 581-598
Kipling, Rudyard. 1907. Just so stories. Garden City, N.Y.:Doubleday.
Pigliucci M, Kaplan J 2000. The fall and rise of Dr Pangloss: adaptationism and the Spandrels paper 20 years later. TRENDS IN ECOLOGY & EVOLUTION 15 (2): 66-70

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copyright ©2003 Michael D. Breed, all rights reserved.Behavior is the culmination of many processes and properties acting together.