The study of animal behavior as observed in the natural environment and in the context of evolutionary adaptation.
The pioneering work of Konrad Lorenz and Niko Tinbergen in the 1930s established a theoretical foundation for ethology, which has had an effect on such wide-ranging disciplines as genetics, anthropology, and political science in addition to psychology. Ethologists believe that an animal must be studied on its own terms rather than primarily in relation to human beings, with a focus on its normal behavior and environment. They study animal behavior from the dual perspective of both "proximate explanations" (which concern the individual lifetime of an animal) and "ultimate explanations" (which concern an animal's phylogenetic past). Proximate explanations answer questions about how a specific behavior occurs; ultimate explanations answer questions about why a behavior occurs.
Much of the field work performed by ethologists is based on the notion that an animal's behavior is generally adapted to its environment in much the same way as its physical characteristics. From the ethologist's point of view, a laboratory environment constrains animal behavior too much to provide a true understanding of its full range of functions and activities. However, the field work of ethologists consists of more than mere passive observation of animals in their natural habitats. In order to make observations about the behavior of an animal in its environment, ethologists often modify that environment. In a now-classic experiment, Lorenz managed to substitute himself for a mother goose, whose goslings then proceeded to follow him in single file wherever he went. In another well-known experiment, Tinbergen conducted a study of ground-nesting black-headed gulls to explain why a mother gull removes all traces of eggshell from its nest after a chick hatches. He hypothesized that the eggshell might be removed to prevent injuries, disease, or the attention of predatory birds. By placing pieces of shell in exposed locations away from the gulls' nests, Tinbergen found that the white interior of the shells were visible from the air and did indeed attract predators.
The ethologist's method of studying an animal begins with the creation of an ethogram, an objective description of its behavior patterns, including hunting, eating, sleeping, fighting, and nest-building. Four types of questions are raised about each activity: the cause of the behavior, development (within the lifetime of the individual animal), evolution (within the lifetime of the species), and adaptive function (how it helps the animal's species survive). Then, the researcher may turn to existing data on related species in various habitats and/or conduct independent research with reference to the animal's natural environment. Experiments may be conducted within the environment itself, or by investigating the effects of removing the animal from that environment. Laboratory studies may also be done, but these will usually be in relation to some aspect of the animal's own habitat.
Early theories of ethology focused on instinctive behaviors called fixed action patterns (FAPs), unlearned actions activated by "innate releasing mechanisms" that were thought to occur in response to specific stimuli. For example, submissive behavior could be regarded as a stimulus triggering an end to aggression on the part of a dominant animal. More recently, the focus of ethological theory has shifted to include an increasing awareness of behaviors that cannot be attributed to innate genetic processes, and learning has come to play a greater role in explanations of animal behavior. One example is the changing attitude toward the key concept of imprinting, first used by Lorenz to describe a nonreversible behavioral response acquired early in life, normally released by a specific triggering stimulus or situation. The differences between imprinting and ordinary learning include the fact that imprinting can take place only during a limited "critical period," what is imprinted cannot be forgotten, and imprinting does not occur in response to a reward. Imprinting was initially regarded as totally innate, but subsequent research has found that conditioning plays a role in this process.
Initially, ethology encompassed broad areas of behavioral study. More recently it has emphasized detailed study of particular behaviors. An emerging subfield, molecular ethology, focuses on how behaviors are affected by a single gene. Additional subdisciplines derived from classical ethology include sociobiology, which also involves gene study, and behavioral ecology, which relates behavior to the ecological conditions in which it occurs.
Moynihan, Martin. The New World Primates: Adaptive Radiation and the Evolution of Social Behavior, Languages, and Intelligence. Princeton, NJ: Princeton University Press, 1976.