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.

Linking adaptations and behavior…the BRAIN!

Neurons = Brain Cells with lots of arms (arms are called �dendrites� and �axons�)

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!

Sea Squirt

Functional mechanisms solve specific problems.

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)

The Comparative Method

Marlin Dolphin

icthyosaur