Animal Behavior and Evolution (Dunbar Ch 1) Psychologists studied Rats… – And made inferences about humans Biologists studied non-humans… – And didn’t The matter of evolution and common ancestry was ignored or avoided

Evolution of Traits What is a trait? Behaviors are traits, just like physical features.

Niko Tinbergen ( ) Studied the flexibility of Instincts – Supernormal Stimuli Supernormal Stimuli Why does an animal exhibit a trait? – This is a question about evolution.

Tinbergen’s “Four Whys” of a Trait 1.How does it change over generations? (phylogenetic cause – Dynamic ‘Why’) 2.How does it change in a lifetime? (ontogenetic cause – Dynamic ‘How’) 3.How does it help survival and reproduction? (functional or ultimate cause – Static ‘Why’) 4.What are the environmental triggers? (motivational or proximate cause – Static ‘How’)

Diachronic versus Synchronic Questions Dynamic view Explanation of current form in terms of a historical sequence Static view Explanation of the current form of species How vs. Why Questions Proximate view How an individual organism's structures function Ontogeny Developmental explanations for changes in individuals, from DNA to their current form Mechanism (causation) Mechanistic explanations for how an organism's structures work Evolutionary (ultimate) view Why a species evolved the structures (adaptations) it has Phylogeny The history of the evolution of sequential changes in a species over many generations Adaptation (function) A species trait that solves a reproductive or survival problem in the current environment

Tinbergen’s “Four Whys” of a Trait Scientific questions (Hypotheses) should specifically address and answer only one “why” at a time. – Some behaviors might be by-products of other traits (Language: Utterances+memory+T.O.M.) – Some (“exaptations”) were selected for other purposes but co-opted for a new one (woodcarving, jewelry-making) – Some may have no function at all – Traits will interact (compete) and be tough to tease apart (Child cries when tired)

The Red Herring of Genetic Determinism Problems – The gene for ___ problem in popular culture. – Genes are linked to fitness (the probability of replication) However, neurons are the engines of adaptability…and humans have a lot of the.

Determinism The Gene’s primary objective is survival and one species – more than others - has evolved the genetic trait of adaptability.

The Evolutionary Approach It’s not about finding causal links between genes and behavior It’s about a strategic analysis of behavior – Why? – What purpose could _____ serve ?

Darwin, Genes, and Behavior Big Considerations: – Which behaviors are (can be) learned and which emerge “without thinking?” – Links between behavior and fitness (increasing health and reproduction) are often indirect. Almost any behavior can be linked to a “fitness” value. How far should we go? – Evolutionary explanations are statistical (individual results may vary!) – Don’t confuse causes of behavior and consequences of behavior.

Darwinian Evolution is not Confined to Genes The (genetic) predisposition for social learning opens the door to culture and non-genetic inheritance. This is still Darwinian.

Our Approach, In Steps 1.Explore particular human behaviors 2.Investigate the cognitive and physiological mechanisms that serve the behavior ( What is the influence of development?) 3.What is the evolutionary history of the phenomenon?

This is how Biologists do it! Physical form has always been explored in the context of function; what does it do to help the animal survive? We don’t have the phylogeny of behavior or language in the way biologists have the phylogeny of morphology. Comparative approaches can help, provided we remember that the tree of life is not a ladder. A related animal is not a direct representation of our past selves.

Behavior is tangled in Culture The emergence of culture (esp. agriculture, 10,000+ years ago), through the ability to share knowledge, may have diminished the selective influence of environment. Cultural evolution, ironically, may have slowed biological evolution. If so, we are stuck with a biological adaptations that were shaped very long ago.