Laboratory Exercises in Animal Behavior - Introduction
Most people assume that animals are just like us, and so endow animals with human feelings and emotions. We say our dogs act "guilty" when we find them on our beds, or our cats are "jealous" of our children. We think of our pets as members of our families, and of wild animals as crafty or cruel or courageous. Although such interpretations of an animal's behavior are acceptable and even useful for most people, they also create some problems. Most of them boil down to one, which is the assumption that animals are "just like us." Why is that a problem? Because animals, like humans, are unique-they aren't "just like us." In some ways we are like other animals, and in other ways we are very different from them. A deeper understanding of animals requires us to think of them as organisms with their own attributes. Instead of assuming that animals "think like us" we must instead "think like them" if we're going to understand them. And, we must be willing to assume, at least for the moment, that animal "thinking" is very different from human thinking.
Some people dedicate their lives to understanding how and why animals do the things they do. Many are trained as veterinarians, but their interest is usually more medical than behavioral. Veterinarians try to ensure the health and safety of the animals in their charge. Usually, this involves yearly check-ups, or tending to sick or injured animals. Only occasionally does a vet become concerned with an animal's behavior, and then usually when the animal is doing something that its owner doesn't like. Animal breeders and trainers are also very interested in how and why animals do what they do. In some cases, a knowledge of animal behavior helps a breeders or trainers to do their jobs, and in others the job is really to make the animal do something in a certain way, or at a certain time. Professional hunters, naturalists, nature photographers, and wildlife artists must also understand animals, because animals are the subjects of their work.
A few people dedicate their lives to understanding animal behavior, not because they need to know about animals to do their jobs, but because it is their job to understand animals. These people use scientific methods to study the behavior of animals, and they are highly trained in specific fields such as biology, psychology, and anthropology. Although they go by various names (for example, ethologists, behavioral ecologists, comparative psychologists, and behavioral primatologists), we will refer to them as animal behaviorists, scientists who study the behavior of animals. Animal behaviorists are an extremely diverse lot-men and women of many different nationalities, races, and ethnic origins; scientists trained in many different fields of scientific inquiry, but they have one thing in common, an interest in and a curiosity about how and why animals do what they do.
We have all been exposed to their work, either directly or indirectly. For example, animals are increasingly becoming the subjects of movies and TV shows-some cable channels specialize in them. Sometimes these shows are inaccurate or excessively "anthropomorphic" (presenting animals as though they were human), but usually these shows are based on work done by animal behaviorists and sometimes they are produced by animal behaviorists. Some of the current practices of wildlife managers, zoo operators, and other animal keepers are grounded in sound principles taken from animal behavior. And, of course, some animal behaviorists, such as Jane Goodall and Diane Fosse, have become famous in our popular culture.
Our purpose in this manual is to expose high school students to the questions and methods used by scientists who study animal behavior. We have three reasons for writing this manual. First, animal behavior has the potential to be very important in our everyday lives. We depend on animals in so many ways, but so few of us understand animals on their own terms. For this reason, educated people should be aware of the information provided by animal behaviorists and their ways of doing things. Second, animal behavior is an excellent example of the workings of science. The scientific study of animal behavior uses the same principles as the other sciences and applies them to a group of organisms that are simultaneously familiar and mysterious. Our society is increasingly driven by scientific information and methods, so it is crucial for educated people to understand the "scientific method." And finally, in our experience, animal behavior is interesting and fun for students to study. Exercises based on the study of animal behavior are therefore an excellent way to motivate students, to get them to think critically, and to show them the power and intrigue of science, as well as its limits and pitfalls.
The Study of Animal Behavior
According to Niko Tinbergen, who won the 1972 Nobel Prize in Medicine along with fellow animal behaviorists Konrad Lorenz and Karl von Frisch, the scientific study of animal behavior has four components: causation, development, evolution, and function. We can describe these components in the form of four questions. (1) What causes an animal to perform a certain behavior? (2) How does the behavior change as an animal develops from conception through death, but especially during its early life? (3) What is the evolutionary history of the behavior? (4) How does the behavior help the animal to survive and reproduce successfully?
Causation of behavior.-Answers to the question, "What causes an animal to perform a certain behavior?" can take many forms. An experimental psychologist might try to identify the stimuli (the events in the animal's external environment) that immediately precede the behavior, and then experiment with these stimuli and their components to understand the stimulus-response relationship of the behavior. A cognitive psychologist might try to understand the mental processes that are triggered by an appropriate stimulus and lead to the performance of the behavior. A neurobiologist might study the anatomy and physiology of single neurons (nerve cells) or of the entire neural pathway associated with the perception of the appropriate stimulus, its processing in the nervous system, and the production of the appropriate motor patterns (the behavior). An endocrinologist might study the role that hormones play in preparing an animal to respond, for example by organizing the nervous system during development and by priming it to respond rapidly. An ethologist might view causation in terms of systems of motivation, and construct conceptual "models" of different systems that identify the appropriate stimuli ("releasers") and the mechanism that produces the behavior ("action pattern"). In a sense, although each of these approaches uses different tools and concepts, all of them are concerned with the way in which a behavior is "triggered" or elicited. Animal behaviorists refer to such investigations as research on "proximate mechanisms" because these triggers are the most closely related to the behavior itself. At the simplest level, we could study reflexes such as the "knee jerk," but usually animal behaviorists are interested in more complex behavior.
Development of behavior.-A different sort of proximate mechanism is one that enables the behavior to come into being as an animal develops from its earliest stages of growth. In many cases, behaviors must be learned and practiced before they are performed appropriately and correctly, so that a portion of the study of development is concerned with the kinds of experience that are necessary and whether the timing of that experience makes a difference in these "learned" behaviors. Animal behaviorists interested in learned behavior might study normal development to identify potentially important kinds of experience, and then experimentally withhold, alter, or shift in time that experience to see whether such manipulations alter normal development. In other cases, behaviors seem to appear rather suddenly, and seem to be correct and complete the first time they are performed. Prior experience seems to have little to do with the development of these "innate" behaviors, although clearly nervous and muscle systems must be properly developed if the behavior is to be performed at all. Such behaviors will develop normally even if animal behaviorists withhold the usual early experiences of young animals. Although animal behaviorists have sometimes made a big deal about the differences between innate and learned behaviors, most now think that they don't really represent completely different developmental processes. Instead, the development of behavior can be viewed as a range of different degrees of "innateness" or "learnedness." Although extremes do exist, most behaviors will fall somewhere between to two extremes.
Evolution of behavior.-At the opposite end of the spectrum of studies of animal behavior are attempts to identify the evolutionary history of a particular behavior. Because the process of evolution (descent with modification) occurs over long periods (sometimes millions of years), experimental manipulations cannot shed any light on evolutionary questions (at least not quickly enough for an animal behaviorist to learn the result). So, evolutionary questions about behavior are addressed by comparing the behaviors of different species of animals. Of course, this "comparative method" requires two things: (1) that the animals being compared are members of an evolutionary lineage, and (2) that we know what that lineage is. Fortunately for animal behaviorists, there are ways to get this information. Today, evolutionary biologists can take information on some aspect of a group of animals, say the structure of some organ, or the sequence of a particular bit of DNA, and with the help of computer programs, come up with an evolutionary "family tree" of these species. Such a "phylogeny" is a hypothesized evolutionary relationship, and if several different analyses based on different information (for example, different bits of DNA and different anatomical structures) all produce the same tree, then we can have some confidence that the proposed phylogeny is correct. If an animal behaviorist then looks at a particular behavior in these same species of animals, it may be possible to determine where the behavior arose (in which species of animal it first appeared) and how in evolved within the phylogeny (did it arise separately more than once, and was it passed on to descendant species). It is even possible for an evolutionary biologist to construct a phylogeny using behavioral characteristics alone, using the same methods and computer programs. Because the evolutionary history of a behavior is far removed from its performance by an individual animal, but is nevertheless an important aspect of that behavior, such analyses are called studies of "ultimate mechanisms."
Function of behavior.-Many students of animal behavior focus their attention on trying to determine whether and how a behavior affects an animal's ability to survive and reproduce. This approach is called the "functional" analysis of animal behavior, and also is a study of ultimate mechanisms because the functions help to shape the evolutionary responses in subsequent generations. According to this approach, a particular behavior is examined to determine whether it enhances an animal's ability to survive and/or reproduce, and if it does, how it enhances survival and/or reproduction. Although this approach can become quite complex, for our purposes here, we will limit such considerations to advantages (functions) to individuals, that is, how the behavior helps those individuals who perform it to live longer, or get mates faster, or get more mates, or have more young, or enhance the survival of their young. If the behavior improves an individual's performance in any of these aspects of "reproductive success" when compared to individuals who don't perform the behavior, then the behavior is said to serve that particular function (for example, the behavior functions to improve survival).
Words of Caution
Several words of caution are appropriate here. One involves the ways in which animal behaviorists talk about behavior versus what they really mean to say. Often animals are said to follow behavioral "strategies" and to make "decisions" or "choices" among stated alternatives. Such statements make it seem as though animals are making conscious, rational decisions the way we do when faced with a set of alternatives. These statements, however, do no imply conscious, purposeful behavior; they refer to functional or evolutionary "choices" or rather, comparisons among behavioral alternatives. So, when an animal is said to "choose" a foraging strategy that provides the maximum rate of food intake, what animal behaviorists really mean is that of the different foraging strategies available to animals, the rate-maximizing one provides the highest survival and reproductive success, so that is why we observe it in animals. In other words, animals aren't aware of the different possibilities and they don't consciously choose one strategy over another. Instead, the animals that use the best strategy (in terms of survival and reproductive success) produce the most offspring, which inherit and follow that strategy. Animals using a poorer strategy leave fewer offspring, and so, eventually, that strategy disappears.
Such functional "choices" mean that the behavior in question must have a genetic basis, but what does that mean exactly? What it surely does NOT mean is that behavior is "controlled" by genes. All behavior occurs as a result of an interaction between an animal's genetic constitution and the environment in which that genetic constitution operates. All it really means is that different individuals have different genetic constitutions, and these differences are responsible for some of the differences in their behavior. An explanation, called the "cake analogy," which was proposed by animal behaviorist Richard Dawkins, is instructive. Suppose a friend gives you a recipe for a great-tasting cake. You copy the recipe and use your copy to make the cake, but your cake tastes terrible. You double check your recipe and discover that you made a small mistake in copying the original recipe-you inadvertently wrote "one T salt" instead of "one t salt." As a result of your small error, your cake contained a tablespoon of salt instead of a teaspoon of salt. No wonder it tasted terrible. But does this mean that the single ingredient (one T salt) "controls" the production of a terrible-tasting cake? Of course not. The entire recipe, plus how you mixed the ingredients, and your oven, and many other factors "controlled" the cake. What is clear, however, is that a small difference in the recipe (or in an animal's genetic constitution) can produce an important difference in the expression of the recipe (or in an animal's behavior).
A very different problem is the "just so story," named by Stephen Jay Gould in honor of Kipling's stories for children. It is very easy for creative animal behaviorists and high school biology students to think up ways in which a behavior might be caused, or develop, or evolve, or function. Remember, however, that just because the idea "makes sense" doesn't mean it's correct. In other words, a "good story" is not necessarily a good explanation. Science involves the proposing and testing of hypotheses, and each idea must be treated as a hypothesis to be tested. You must think of ways to test your idea (your proposed hypothesis), and the tests should be attempts to disprove your idea, rather than to prove it.
In many cases, several hypotheses might exist to explain a particular behavior. We might be tempted to test each separately, for the sake of simplicity, but there is a danger in that simplicity as well. The danger is that results that support one hypothesis are likely to support others as well, and when this happens, we cannot eliminate any of these hypotheses (remember, we should try to disprove each hypothesis). An alternative, "stronger" method is to test many or all of the hypotheses at the same time. This method of "multiple working hypotheses" has the advantage of eliminating many or all of the hypotheses at once, so that our understanding can be increased rapidly. It also requires, however, that each hypothesis make at least one unique prediction (that is, a prediction that none of the other working hypotheses make), and sometimes such critical predictions simply do not exist.
We should also warn you of another potential problem. You are attempting to answer questions about an animal's behavior, but you are using your own senses to gather information about that behavior. Unfortunately, your senses do not produce prefect reproductions of the world around you, and your senses may be quite different from those of your animal subjects. Some animals can see light that we cannot see, and some can hear sounds that we cannot hear. Some animals have senses that we don't seem to have at all-some can detect electric or magnetic fields, for example. In other words, the "sensory world" of your subject animal may be very different from you own, so the animals may be using cues that you cannot perceive at all.
A related problem has to do with expectations, rather than sensory capabilities. In many cases, we know that people see "what they want to see" rather than what really happens. A clever animal behaviorist once described this phenomenon as: "I wouldn't have seen it if I didn't believe it."
A final problem can be called the "eye witness" phenomenon. If five people are eye witnesses to a crime, it is quite common for them to give five different descriptions of the perpetrator. Sometimes the accounts can differ radically-one witness might say the assailant was a white older man, another that she was black teenager. In addition, a particularly persuasive and confident witness can often sway the others, even when the confident one is wrong.
Some of the challenges facing animal behaviorists involve finding ways to overcome these and other problems inherent in scientific research. Remember that although the scientific method attempts to be objective, it is practiced by people, who cannot be objective. Each of us has opinions and beliefs, which will affect the ways we see and interpret things.
Words of Encouragement
On the other hand, despite the challenges facing students of animal behavior, progress has been steady and rapid. Many species of animals have been studied, from invertebrates to humans, and both proximate and ultimate mechanisms have received lots of attention. We know quite a bit about neural and physiological mechanisms, about the ways in which animals learn, about how behavior develops, and what functions behaviors serve, and we are beginning to see the evolutionary history of behavior unfolding. It's an exciting time for animal behavior because our field seems to be coming into its own. One of the important next steps that animal behaviorists now face is "spreading the word" to others. We hope to show you, through these exercises, that animal behavior is an interesting and important field of science. Although most of you won't become animal behaviorists, all of you can learn to appreciate what animal behavior has to offer, and all of you can learn something about real science as you learn about animal behavior.
