levels of analysis in ethology - wsu...
TRANSCRIPT
Levels of Analysis in Ethology • Ethology: the study of animal behavior • Example: Why do male monkeys fight? • Niko Tinbergen 1963 �On Aims and Methods in Ethology� • Answer questions about WHY behaviors occur • Four levels of analysis
– Proximate • Causal • Developmental
– Evolutionary • Phylogenetic • Functional
• Not mutually exclusive
Evolutionary Levels of Analysis: Over many generations of lifetimes
• Phylogenetic Level – Understanding a
behavior/trait by examining relationships with other species over evolutionary time
• Functional Level – Understanding
how a behavior/trait was designed by natural selection to facilitate reproduction
Functional Level of Analysis
• Was the behavior/trait designed by natural selection to facilitate reproduction in the ancestral past?
• What is the function of the trait/behavior? • Is the trait an adaptation?
Adaptations
• An adaptation is a trait with a functional role in the life trajectory of an organism that evolved by natural selection.
• Adaptations transform their surroundings in specific ways that facilitate the reproduction of the genes that made those traits.
• Adaptations can be structural or behavioral. – Structural adaptations are physical features of an organism (shape,
body covering, armament; and also the internal organization). – Behavioral adaptations are include instincts and/or the ability to learn.
Examples include searching for food, mating, fight-or-flight, and vocalizations.
Neural circuits process electrochemical information that produce thought/feelings/behavior
(materialism!)
Movement, the Brain, and Behavior
• The brain is connected to the spinal cord; spinal cord connected to nerves; nerves send impulses between brain and body�s other tissues to create movement
• �behavior��is movement in the body guided by the brain – think sea squirts: only need
brains in motile phase of life; when done moving around, they �reabsorb�—their own brains!
Functional mechanisms have specific design features that solve specific problems.
Most configurations will not solve the problem.
What kinds of functional mechanisms are selected?
• Those that facilitated reproduction, both directly (uteruses) and indirectly (hearts), in an organism’s ancestral past.
• These functional mechanisms are called adaptations. • An organism can be thought of an integrated set of
adaptations. • Adaptations show evidence of design: a strong, though
not necessarily perfect, fit between the mechanism and the reproductive problem it was selected to solve…natural selection is more of a tinkerer than a goal-directed engineer. (Bad backbones, etc.)
Adaptation/Functionality
How do you identify an adaptation?
(1) Design Analysis (2)!Compara+ve!method!
Analysis of Design Harvey dissected the heart and learned that the heart functions to pump blood by examining what he saw: chambers, strong muscles that expand and contract the chambers, arteries through which blood leaves a chamber and gets to other tissues in the body, valves to keep it from flowing backwards, etc.
Analysis of Design Adaptations show
evidence of: • Precision • Economy • Efficiency • Constancy • Complexity • Reliability
George!Williams!
Analysis of Design
• Problems: – It is subjective…but let�s be reasonable – Adaptations are not always perfectly-designed,
hindering our ability to see, for sure, what their functions are (human spine)
– The function of an adaptation is not always obvious, even though we KNOW they are adaptations (e.g., human bipedalism)