Summary Behavioural Biology
Chapter 1: The Science of Animal Behaviour
1.1 - Animals and their behaviour are an integral part of human society
Understanding the behavior of animals has always been important to people. Beginning in prehistoric
times and continuing for tens of thousands of years, humans painted images of animals on cave walls all
over the world. These drawings are detailed enough to allow us to identify different species (both extinct
and extant), and many images depict animals exhibiting behaviors. Because humans in prehistoric times
relied on animals for food, knowledge about animal behavior was important for survival. Animals and
animal behavior are still an integral part of society. Millions of people live and interact with animals daily
and many people work with animals. Cattle, chickens and turkeys, hogs, and sheep are important
agricultural products; horses are used by ranchers, law enforcement officials, and the horse-racing
industry; and dogs have long been used in both police work and the military. In all these cases, people
manage animal behavior to accomplish a task. In a different way, the behavior of animals is also integral
to medicine. It helps researchers assess and learn about sensory, motor, and cognitive functions. For
instance, behavioral changes often reflect the effects of neurochemical agents, neurotoxins, or hormonal
changes, which can be more easily studied in animals than in humans. Research on memory, cognitive
function, and learning often involves measuring and recording animal behavior. In addition, animals
provide entertainment for millions of people. Animal behavior researchers use the scientific method to
understand the behaviors we observe. So what exactly do we mean by behavior?
Recognizing and defining behavior
We define animal behavior as any internally coordinated, externally visible pattern of activity that
responds to changing external or internal conditions. Internally coordinated refers to internal
information processing such as endocrine signaling, sensory information processing, or the action of
neurotransmitters. Externally visible activity refers to patterns that we can observe and measure. We
can observe an animal’s behavioral response to changing conditions. For example, male crickets, frogs,
and birds vocalize in response to changes in day length, temperature, or moisture at specific times of the
year. Lizards are ectotherms, they cannot regulate their body temperature internally but can do so
behaviorally.
Measuring behavior: elephant ethograms
Behaviors must be measurable - we must be able to quantify our observations with numbers according
to specific rules - and different people must be able to recognize a behavior independently. Often, such
characterization begins when a trained observer completes an ethogram, which is a formal description
or inventory of an animal’s behaviors. Ethograms typically list or catalogue defined, discrete behaviors
that a particular species exhibits. Researchers can use an ethogram and measure how many times a
behavior occurs (its frequency), the length of time of a behavior (its duration), the frequency of the
behavior per unit time (its rate), or the vigor or forcefulness of the behavior (its intensity). Typically, a
more complete list of behaviors that occur over a specific time period is recorded. From these
observations, a researcher can then determine both the total and the relative time that an animal
engaged in each behavior - the measure of the behavior divided by the overall time spent observing the
animal. The resulting time budget indicates the total time and relative frequency of each behavior. Paul
Rees created an ethogram for captive Asian elephants. When elephants were in their outdoor enclosure,
he recorded their behavior every five minutes for an entire day once a week for 11 months. His
,ethogram contains 15 behaviors, including feeding, standing, and digging. In addition, he measured
stereotypic behavior, or captivity induced behavioral anomalies that are used as an index of the welfare
of captive animals. These behaviors often include repetitive behaviors that lack an apparent purpose,
such as head bobbing or pacing. Rees found that captive elephants spent about a quarter of their time
feeding, and that stereotypic behavior was negatively correlated with feeding behavior. Rees suggests
that using widely spaced feeders to supply food slowly and at random times could reduce the frequency
of stereotypic behavior.
1.2 - The scientific method is a formalized way of knowing about the natural world
Science was obtained by human beings seeking to understand the natural world. Scientists engage in the
process of science, which involves observing events, organizing knowledge, and providing testable
explanations. The process of science is fundamental to our understanding of the natural world.
The importance of hypotheses
In the humanities, researchers are interested in understanding the human experience. The social
sciences involve knowledge of human behavior and societies. And in the natural sciences, researchers
strive to understand the natural world. Scientists begin with questions, but they formulate these
questions into hypotheses. Hypotheses are explanations that make predictions that can be tested.
Because these tests can be repeated and confirmed by other scientists, their results are much less
subject to debate.
The scientific method
Scientists use the scientific method to learn about the natural world. The
scientific method is a formalized process that involves the testing of
hypotheses. This process often begins with an observation of a single
event or pattern that requires explanation. This observation forms the
basis of a research question - a brief statement of something that we
would like to understand. The identification of patterns can be
accomplished with careful observation and mere human curiosity. The
next step in the scientific process is the formulation of a hypothesis, or,
more formally, a research hypothesis. A research hypothesis is an
explanation that is based on assumptions and produces a testable prediction. Research hypotheses are
evaluated using two statistical hypotheses that reflect the two possible outcomes. One outcome is that
the proposed explanation for the observation does have a significant effect; this is the alternate
hypothesis, or Ha. The other possible outcome is that the proposed explanation does not have a
significant effect; this is the null hypothesis, or H0, the hypothesis of no effect. Together, the null and
alternate hypotheses are known as statistical hypotheses. The last step in the scientific process is to
evaluate the research hypothesis by testing the prediction of the null hypothesis. When scientists find
support for a research hypothesis, we do not conclude that the hypothesis has been “proven” to be
correct. Scientists can never prove that a hypothesis is correct because random chance or an untested
variable (a different alternate hypothesis) could also have led to the observed phenomenon. So all a
scientist can do is test the hypothesis repeatedly and always fail to reject it. As a result, all hypotheses
are tentative explanations of observed phenomena. They may eventually be rejected and replaced by
hypotheses that make more accurate predictions. Scientists can, and do, test multiple hypotheses
simultaneously to formulate explanations of observations of the natural world that can facilitate rapid
scientific advancements. When the null hypothesis cannot be rejected, you need to develop a new
,research hypothesis to explain the original observation. This might involve a slight modification to the
rejected hypothesis or something radically different.
Negative results and directional hypotheses
Sometimes scientists do not reject the null hypothesis, a situation known as negative results. Negative
results indicate that the alternate hypothesis does not explain the behavior being examined. This is an
important part of the scientific process. Scientists need to develop a new alternate hypothesis to explain
the observation. Hypotheses can also be directional or nondirectional, depending on their specificity. A
directional alternate hypothesis predicts specifically how the variable under examination will affect a
particular behavior - positively or negatively - whereas a nondirectional alternate hypothesis usually
offers no specific prediction of how the variable will affect behavior. Researchers use a nondirectional
hypothesis when they do not have a specific prediction about an animal’s response.
Correlation and causality
The data you collected represent a correlation between the two variables measured: they co-vary, or
vary together, predictably. Correlations can be positive, when both variables display either low or high
values simultaneously, or negative, when one variable displays high values while the other displays low
values. In addition, correlations may be zero, which occurs when two variables vary independently of
each other. Correlation does not demonstrate causality. That is, even if two variables are correlated, one
does not necessarily cause the other. Because correlation does not demonstrate causation, researchers
often try to rule out plausible alternative explanations. They also try to find a mechanism that might
underlie the correlation. Scientists place a premium on mechanistic explanations for patterns because
mechanisms help to explain why the pattern occurs and thus strengthen their conclusions. Because it is
very difficult to rule out all other possibilities, it can be very difficult to establish causality through
observation alone. Many scientists therefore test hypotheses using controlled experiments, but even
experiments cannot prove a hypothesis is correct.
Hypotheses and theories
The more times a hypothesis has been tested and not rejected, the more confidence the scientific
community has in the explanation. Hypotheses that make many predictions, have been tested hundreds
or thousands of times by many different scientists, and have not been rejected come to be known as
scientific theories. Scientific theories provide a conceptual framework that explains many phenomena
and are well supported by observations and experimental tests. Scientific theories are hypotheses that
have been tested repeatedly. They are more general than specific hypotheses and tend to unify and
simplify our knowledge by synthesizing information into a larger framework.
Social sciences and the natural sciences
Social scientists create and test hypotheses using the scientific method to study human behavior and
societies. Their methodology often includes collecting data from surveys, questionnaires, and public
opinion polls, as well as conducting experiments to obtain information about human values, perceptions,
and behavior. Alternatively, social scientists could conduct an experiment. Animals are a part of the
natural world, and so it makes sense that animal behavior is a part of the natural sciences. Psychologists
have two ways to study human behavior: (1) directly or (2) indirectly, through the study of animals, in
the same way that medicine uses animal models to understand human health. Psychological research on
the evolution of human behavior often involves the study of our closest relatives. Animal behavior
research, whether conducted by biologists or psychologists, uses the scientific method to formulate and
test hypotheses.
, 1.3 - Scientists study both the proximate mechanisms that generate behavior and the
ultimate reasons why the behavior evolved
Many birds travel long distances between summer breeding and winter nonreproductive grounds. The
seasonal movement of individuals between these locations is known as migration behavior. We can ask
several questions about this behavior - what causes migration? The behavior often is initiated by
seasonal changes in day length. These changes trigger hormonal responses that lead to increased
feeding, fat deposition, and the onset of long-distance movement. In some species, migration behavior is
genetically determined and requires no learning, while in others, migration routes must be learned by
following experienced individuals. We can also ask, “Why do birds migrate?” Migration allows individuals
to track resources and thus avoid places where resource availability is greatly limited in some seasons; in
short, it promotes survival. To understand the evolution of migration behavior for a particular population
or species, researchers often examine how migration patterns differ among different populations of a
species or between closely related species. Niko Tinbergen summarized the different types of research
by outlining four basic questions that can be asked about animal behavior:
1. What is the mechanism that causes the behavior?
2. How does the behavior develop?
3. What is the function of the behavior?
4. How did the behavior evolve?
Tinbergen’s four questions provide a framework for the study of behavior. Answers to Questions 1 and 2
are often referred to as proximate explanations, because they focus on understanding the immediate
causes of a behavior. These explanations often incorporate studies of genetics, sensory systems,
neurons, hormones, and learning. Answers to Questions 3 and 4 are known as ultimate explanations,
because they require evolutionary reasoning and analysis.
1.4 - Researchers have examined animal behavior from a variety of perspectives over time
From Darwin forward, animal behavior research has been based on evolutionary thinking. However,
during this time a large number of rich and diverse research foci have placed different emphases on
Tinbergen’s four questions and have developed varied approaches and methodologies.
Darwin and adaptation
In his first book, Darwin discusses instinct, or behaviors neither learned nor requiring experience. One
intriguing example he describes is cuckoo reproductive behavior. Many species of cuckoo lay their eggs
in the nests of other species, which then care for the young. How could such behavior evolve by natural
selection? Darwin notes that while most female birds lay an egg every day, female cuckoos do not: they
lay one egg every several days. Darwin hypothesizes that selection would favor an individual that laid her
eggs in the nests of others. Darwin’s work on animal behavior is wide ranging, both taxonomically (e.g.,
ants, birds, and bees) and topically (e.g., reproduction, aggression, and instinct). Although some of
Darwin’s descriptions are based on anecdotes and others are anthropomorphic, he always explains
behavior using evolutionary reasoning and in terms of adaptation.
Early comparative psychology
Comparative psychologists study animal behavior in order to understand human behavior. Romanes
systematically examines the reasoning ability of a wide variety of animal taxa, ranging from protozoans
to mammals. For him, an animal displays a “mind,” or conscious action, rather than mere reflex reaction,
when it uses previous experiences to learn and modify its behavior in an adaptive manner. While
