Development of traits:VariationHeritabilityNatural selection / adaptednessKey factor is selection pressureAre we dealing with common descent or with convergence?Common descent: we lijken meet op apen omdat deze dichterbij liggen in de evolutieConvergence: unrelated species have come up with similar solutions to similar problems Homology: a trait is of common descentAnalogy: a trait is functionally similar but was not derived from the same ancestorFalse dichotomies in evolution studies:Innate – acquired/learnedGenes – environmentInstinct – learningNature – nurtureWhat is innate? Different opinions:Present at birthBehavioural difference caused by a genetic differenceAdapted over the course of evolutionUnchanging throughout developmentShared by all members of a speciesPresent before the behavior serves any functionNot learnedLorenz: behavior can be dissected in innate and acquired/learned components. Animals reared in complete isolation would show behavior that is completely innate, = Kaspar Hauser experimentLehrman: behavior is the result of a complex interaction between the individual and its internal and external environment. No new neurons are generated after birth. At birth there are (too) many synaptic connections, so pruning takes place. Does absolute size matter? No, if the body is bigger, the brain is too. So look at relative size. Cortex size does matter. Forebrain complexity is characterized by cell groups. Brains tend to get bigger and bigger. Why? 3 hypotheses:Foraging hypothesis: differences in brain size are due to differences in the way animals get their food. Social intelligence hypothesis: the more social interactions are needed (larger social group), the larger the brain (relatively). General intelligence hypothesis: species differences in social learning and innovation are linked to brain volume. Group size does not covary with primate general intelligence score. Summary:...