Ethology is a subdivision of biology that focuses on animal behavior that is innate—a study of animal behavior that holds the belief that most of what animals know is instinctive, not learned. Instincts are genetically programmed behaviors; they generally serve to galvanize the mechanisms that evoke the animal to act or react. Ethology, as a discipline, developed in Europe and became popular in the early 1900s. As a study of animal behavior, ethology also deals with the question of nurture versus nature, focusing on the natural environment and the physiological aspects in that environment. Unlike animal behaviorists, who are generally interested in learned behaviors, ethologists focus on innate behaviors— that is, the behavior developed during ontogenetic development. According to one theory, for example, ducks learn to “quack” like ducks and don’t “honk” like geese because the chicks hear their parents while in the egg; thus, they learn to “quack.” Early ethologists noted for their work were Herbert Spencer, Charles Darwin, G. J. Romanes, and William James. Major modern ethologists include Konrad Lorenz, Nikolaas Tinbergen, and Karl von Frisch. These modern ethologists unveiled four basic strategies by which genetic programming directs the lives of animals: sign stimuli, motor programs, drive, and imprinting.
Sign Stimuli: A sign stimulus is an external sensory stimulus that triggers a typical, innate behavior (fixed-action pattern). It allows animals to recognize and react appropriately to important objects or individuals they interact with for the first time. For example, baby herring gulls know from birth to whom they direct their begging calls in order to be fed. They also know how to trigger the regurgitation action in their parents in order to receive the food. However, the chick does not recognize the parent itself. It solely relies on the sign stimulus of the vertical line of the herring gull bill and the red spot on the tip of the bill (pecked at to induce regurgitation). Almost any model presenting this visual image would evoke the same reactions from the chicks. Another example involves the graylag goose and its unaltered egg-retrieval pattern. If it sees an egg outside of the nest, the goose rolls the egg with its beak back to the nest using side-to-side head motions. However, the fixed-action pattern is such that any object resembling an egg is rolled to the nest even though it may not be incubated. Fixed-action patterns are innate behavioral patterns that are triggered by sign stimuli. They are carried out to completion even if other stimuli are present or if the behavior is inappropriate (the graylag goose and nonegg objects).
Sign stimuli aren’t solely visual. They may be tactile or olfactory, such as in the case of pheromones. The most customary uses of sign stimuli in wildlife are in communication, food gathering, and in warning signals. The various types of communication include visual, chemical, and mechanical communications. Mechanical communication is primarily performed through vibrations through the ground or air. Chemical communication largely includes pheromones that one animal emits to influence the behavior of another species or that of the other gender. Sign stimuli are also used in courting and mating. They are especially prevalent among animals that are usually solitary except during the sexual part of their lives. Sticklebacks, for example, use a system of inter-locking releasers to organize their mating. When the sticklebacks’ breeding season arrives, the male’s underside turns bright red. While the color attracts females, it also provokes other males to attack. As a female approaches the “red” male, she reveals her belly, which is swollen with eggs. This rouses the male to perform the mating dance and then lead the female to his nest. Through a series of movements, the male induces the female to release her eggs so he can fertilize them. If the female is induced in any other way other than the specific movements of the fertilizing male, the male stickleback will not fertilize the resulting eggs, but will eat them instead.
Motor Programs: Motor programs are chained sequences of specific muscles coordinated to perform a single task. Mating dances, stinging actions, and nest making are all examples of motor programs. There are two classes of motor programs. One is entirely innate (fixed-action patterns), and the other is learned. The first class of motor programs is largely applicable to animals, while the second is largely applicable to humans. The egg-rolling mechanism in geese has been a source of great curiosity to ethologists. The sign stimulus is the egg (or any other round, egglike object); however, the actual act of rolling the egg to the nest is a motor program. It has been recorded that the goose will continue rolling the egg cautiously into the nest even after the egg has been removed. The goose itself does not “think” about performing this act, rather it is inclined to it by the sign stimulus of a round object.
The second class of motor programs includes those that are learned. For example, in humans, bike riding, shoe tying, speaking, swimming, and walking are all learned. However, after a certain amount of time and practice, they become so much part of the norm that they can be performed without full conscious attention. They become so almost innate that they can be performed without normal feedback. An example of this class of motor programs in animals is that of the songbird. Though the songbird needs its audio abilities to sing, once it has learned the “songs,” it no longer needs to hear what it is singing. This also applies to humans. Once a person learns to speak, no matter if he goes deaf, he can still speak. These motor programs need to be wired early on in development, so that later in life, they become nearly instinctive.
Drive: The third general strategy of ethology is drive. Drives are generally defined as desires or subconscious instincts that are switched on and off depending on inborn timers and chemical releasers. The stickleback, for example, normally is a solitary creature that neither lives with other individuals of its species, nor wishes to. However, at the stage of sexual reproduction, a sign stimulus is formed (the red belly), a drive to reproduce is created, and a motor program is carried out (the series of movements the male performs to induce the releasing of eggs). Drives are the inborn senses that are awakened when animals need to migrate or hibernate. In some frogs and reptiles, for example, as the weather becomes colder, the blood cells perform reverse osmosis in which the cells become extraconcentrated with salt as the diluted water outside of the cells freezes. In essence, these animals freeze during the winter and thaw out once the weather turns favorable. Other stimuli that trigger drives are lengthening or shortening of days. Spring migration and courtship behavior are triggered by the lengthening of daylight, while the shortening of daylight triggers winter migrations and certain cryogenic methods in animals.
While drives are put to sufficient use in the wild, in domestic animals, they are usually pent-up. The effect of this unused motivation is evident in cats. Even though these animals are well fed, they chase and stalk small animals, insects, or toys. In severe cases, they might even attempt to kill, devour, or disembowel imaginary targets. This behavior can occur without a proper stimulus or, in some cases, without even an apparent stimulus. However, as the desires and motivations of wild animals are exercised, they “learn” to ignore normal, repetitious stimuli if no threat or reward exists. Then, as soon as an abnormal stimulus occurs, normal reactions take place.
Imprinting: Imprinting is an example of programmed learning. It is described as the capacity to learn specific types of information at certain critical periods in development. This method of learning is displayed in the young of certain species. Ducks and other bird chicks must be able to recognize their own parents from other adults of the same species. This is also apparent in humans. Babies seem to know their mothers within a few months of birth. They cry and bring attention to themselves when they know they are being held or coddled by unknown persons. While in humans, this process can actually be described as learning and can afford to take a few months’ time, in animals, this process of recognition must occur from birth. This immediate identification is accomplished through evolutionary wiring. Ducklings, for example, are wired to follow the first object they see moving that produces the species-specific call. The call triggers a drive in the duckling to follow the object. As long as the object makes the right calls and moves, the ducklings will follow a varied list of objects, such as rubber balls, cans, and humans.
The parental-imprinting phrase is brief, about 36 hours after birth. Another phase of imprinting occurs when the newborn matures and is about to begin mating. While some of the imprinting is helped along by genetics, most is learned, thus making imprinting the only ethological strategy that relies heavily on learning.
Other Areas of Research in Ethology
There are many strategy specific branches in modern ethology. The new areas of research include comparative ethology, analysis of behavioral patterns, and human ethology.
Comparative ethology is a field that tries to find relations in common behavior between animals with a common ancestor that performed this behavior. The primary mission is to investigate biological and behavioral similarities and differences between two different species and make a connection as to why either occurs.
Analyses of behavioral patterns are prevalent not only among animals, but among humans as well. Analysis has been taking place on the observational, neural, and molecular levels. Sensatory learning abilities have been proposed and tested. Mating behaviors and aggressive behaviors have also been thoroughly researched and explained.
Human ethology is a field that compares our own behavior to that of our closest evolutionary relatives, and through a roundabout way, comes to understand our own behavior. Human ethology is also closely related to comparative psychology, a field that discusses the psychological patterns and relations among our genus. Origins of such phenomenon, including origins of nonverbal communication, social behavior, and grooming are explored by human ethologists. New aspects of human ethology include human behavior, genetic psychology, psychobiology, and behavior evolution. The evolutionary basis of human behavior and methods of how to observe and record human behavior are also addressed by this subject. Thus, human ethology goes hand in hand with psychology but has a biological twist. It focuses on evolutionary and genetic traits that are species specific, and on other behaviors that humans have in common with other animals.
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- Hailman, J. P. (1967). An introduction to animal behavior: Ethology’s first century. Englewood Cliffs, NJ: Prentice Hall.
- Lorenz, K. Z. (1981). The foundations of ethology. New York: Springer-Verlag.
- Lorenz, K. Z. (1996). The natural science of the human species: An introduction to comparative behavioral research. Cambridge: MIT Press.