Chapter 1
Types of Questions and Levels of Analysis
Ethology: the study of animal behavior
Humans have always thought and acted like ethologists
Ethologists pose four distinct types of questions, which Niko Tinbergen outlined
Mechanism: What stimuli elicit behavior? What sort of neurobiological and hormonal changes occur in response to, or in anticipation of, such stimuli?
Development: How does behavior change with the ontogeny, or development, of an organism? How does developmental variation affect behavior later in life?
Survival value: How does behavior affect survival and reproduction?
Evolutionary history: How does behavior vary as a result of evolutionary history or phylogeny? When did a behavior first appear in the evolutionary history of the species under study?
Tinbergen’s four questions can be captured into two different kinds of analyses
Proximate analysis: focuses on immediate causes
Ultimate analysis: centers on evolutionary forces that have shaped a trait over time
Proximate analysis incorporates Tinbergen’s first two questions and ultimate analysis incorporates the last two questions
Example of proximate analysis:
Why do some bird chicks peck at red stimuli but not stimuli of other colors? Does red trigger a set of neuronal responses that are not triggered otherwise? If so, exactly which neurons and when?
Example of ultimate analysis:
What selective forces in the birds’ evolutionary past would have favored individuals that had responses to red stimuli? Was the color red associated with a particular food source? Do other closely related bird species show similar responses to red stimuli?
What is Behavior?
Early on ethologists like Tinbergen defined behavior as “the total movements made by the intact animal” but this definition is far too general, incorporating almost everything an animal does
In many instances, behavior has a genetic basis
Behavior: is the coordinated responses of whole living organisms to internal and/or external stimuli
Three Foundations
Evolutionary change has shaped the diversity of life and how the primary engine of that change is a process called natural selection
Darwin argued that any trait that could be transmitted (heritable) across generations and provided an animal with some sort of reproductive advantage over others in its population would be favored by natural selection
Natural selection: The process whereby traits that confer the highest relative reproductive success on their bearers increase in frequency over generations
Whereas natural selection changes the frequency of different behaviors over the course of many generations, individual learning, can alter the frequency of behaviors displayed within the lifetime of an organism
Cultural transmission: a transmission system in which animals learn through various forms of social learning
Cultural transmission affects the type of behavior animals exhibit and the frequency with which behaviors occur and can allow newly acquired traits to spread through populations at a very quick rate, as well as permit the rapid transmission of information across generations
Natural Selection
Theory of natural selection applies to behavioral traits as well as morphological, anatomical, and developmental traits
Indeed, morphological traits are often the physical underpinning for the production of behavior, so morphology and behavior are linked at many levels
Xenophobia: a fear of strangers
Xenophobia may be especially strong when resources are scarce, since competition for such resources will be intense then, and keeping strangers away may have an especially strong impact on the lifetime reproductive success of group members
Individual Learning
Just because the use of a behavior is changing with the course of an individual’s lifetime does not mean that natural selection is not occurring
It is certainly possible for natural selection to operate on the ability to learn, that is, natural selection might favor the ability to learn which individuals make good mates over the lack of such an ability
Cultural Transmission
The information-center hypothesis, which posits that foragers may learn critical pieces of information about the location and identity of food by interacting with others that have recently returned from foraging bouts
The information acquired via individual learning never makes it across generations
In contrast, with cultural transmission, if a single animal’s behavior is copied, it can affect individuals many generations down the road
Cultural transmission has both within and between generation effects
If there is variation in the tendency to copy the behaviors of other, and that variation is due to certain types of genetic variation, then natural selection can act on the tendency to use culturally transmitted behavior
Conceptual, Theoretical, and Empirical Approaches
Conceptual approaches to ethology involve integrating formerly disparate and unconnected ideas and combining them in new cohesive ways
Kin selection expanded the bounds of classic natural selection models by demonstrating that natural selection not only favors behaviors that increase the reproductive success of individuals expressing that behavior, but also favors behaviors that increase the reproductive success of those individuals’ close genetic kin
Hamilton proposed that fitness is composed of two parts:
Direct fitness: is measured by the number of viable offspring produced, plus an effects that individual 1 might have on the direct descendants of its own offspring
Indirect fitness: effects are measured by the increased reproductive success of individual 1’s genetic relatives—not including its offspring and any lineal descendants of offspring— that are due to individual 1’s behavior. These actions indirectly get copies of individual 1’s genes into the next generation
An individual’s inclusive fitness is the sum of its direct and indirect fitness
Theoretical Approaches
Theoretical approach: entails the generation of some sort of mathematical model of the world
During the formative years of ethology, much theoretical work focused on animal foraging behaviors
Optimality theory searches for the best (optimal) solution to a particular problem, given that certain constraints exist in a system
A good theory will whittle away the details of specific systems, but just enough to allow for general predictions that can apply to many systems
Empirical Approaches
Empirical studies boil down into two types:
Observational studies: involves gathering data on what animals do, without attempting to manipulate or control and ethological or environmental variable
Experimental studies: experimentally manipulating a system to demonstrate causality
Does theory come before or after empirical work?
It depends
Good theory can precede or postdate data collecting
On some occasions, an observation or experiment will suggest to a researcher that the results obtained call for a mathematical model of behavior to developed
Theoretical models can inspire empirical research
Summary
The scientific study of animal behavior, which dates back hundreds (if not thousands) of years, is called ethology.
The process of natural selection, the ability of animals to learn, and the process of cultural transmission are all important concepts for developing an integrative view of animal behavior.
Niko Tinbergen suggested that ethologists ask four types of questions: What are the immediate causes of behavior? How does behavior change as an animal develops and matures? How does behavior affect survival and reproduction? How does behavior vary as a function of evolutionary history?
Ethologists examine behavior from a proximate perspective by examining immediate causes of behavior, and from an ultimate perspective by examining evolutionary factors responsible for a behavior.
Work in ethology, like in all scientific fields, can be conceptual, theoretical, or empirical. Empirical work can be further subdivided into observational and experimental studies.