Lecture 2: Overview of Darwinian Theory PDF

Lecture 2 Overview of Darwinian Theory “Deep Time” (McPhee, 1981) Geological Time Scale After-the-Fact Method “We believe what we want to believe”- Demosthenes X1, X2 , X3..... ---------------------------------O Possible Causes Observation Examples from Psychology: Psychoanalysis, Operant Con...

Lecture 2 Overview of Darwinian Theory “Deep Time” (McPhee, 1981) Geological Time Scale After-the-Fact Method “We believe what we want to believe”- Demosthenes X1, X2 , X3..... ---------------------------------O Possible Causes Observation Examples from Psychology: Psychoanalysis, Operant Conditioning Theories Focus on Ontogenetic Causes Why do males outperform females on tests of mental rotation ability? Traditional Explanations: - differential experience - hormonal factors - brain lateralization Evolution = Change Over Time Lamarck’s Theory of Acquired Characteristics • organisms are always adapted to their environments • environments change over time •laws of use and disuse • structural changes passed to the next generation Scientific Observations Pre Darwin 1. Biodiversity Scientific Observations Pre Darwin 2. The Earth is Old • Charles Lyell: Principles of Geology • Change due to natural forces • Earth older than previously thought Scientific Observations Pre Darwin 3. Organic Structures Change Over Time Scala Naturae- Aristotelian Finalism Structural & Developmental HOMOLOGIES Scientific Observations Pre Darwin 4. Structures Have A Purpose 4. Structures Have a Purpose/Function / Function H.M.S. Beagle (1831 - 1836) Galapagos Islands Tortoise Shells and Finch Beaks Descent with Modification • All organisms are related through descent from a common ancestor that lived in the remote past. • Organisms share many characteristics. • Over evolutionary time, the descendants of the common ancestor have accumulated diverse modifications or adaptations that allow them to survive Why Do Species Change? Adaptation: Animals that survive are the ones best suited to the environment Key Influences: 1. Artificial Selection: breeding for traits 2. Thomas Malthus : Essay on Principle of Populations- competition for resources Origin of Species (1859) Natural Selection: process by which the form and behavior of organisms in a population that are best adapted to the environment increase in frequency relative to less well adaptive forms, over a number of generations Theory of Natural Selection • NS occurs when some inherited variations lead to greater reproductive success than other inherited variations. • Changes over time due to differential reproductive success. • Traits which are adaptive tend to be passed on while those which are maladapted or less adapted, tend to disappear over evolutionary time. • Tiny variations accumulate and eventually new species branch off. Origin of Species (1859) Mechanism of Natural Selection Four Necessary Conditions: 1. Reproduction 2. Inheritance 3. Variation 4. Competition Reproduction • Organisms must reproduce to form new generations Inheritance • If there was no mode of inheritance whatever adaptive characteristics there are in parents would be lost in next generation Variation Organisms must possess heritable variations Competition • Struggle for existence • Limited Resources Applications To Psychology “in the distant future, psychology will be based on a new foundation, that of the necessary requirement of each mental power and capacity by gradation” Why do people exhibit ethnic prejudice? Social Psychology Behaviorism • Categorize people differently on basis of observable characteristics • Group biases • Stimulus Generalization Proximate vs. Ultimate Causation • Proximate Questions (What & How) • How does the human visual system perceive depth? • How do neonates bond with parents? • What is ethnic prejudice? • Proximate Explanations • Focus on development of the individual (ontogeny) • Includes physiology, social experiences, genetic factors, parenting techniques etc. Proximate vs. Ultimate Causation • Ultimate Questions • Why do humans perceive depth • Why do we love our children? Our parents? • Why do we treat people who are different on some dimension differently than we treat people who are similar to us? • Ultimate Explanations • Address the adaptive significance of a trait or behavior over evolutionary time (phylogeny) Proximate and Ultimate Analyses • Not separate or incompatible • Can mutually inform each other • Jointly provide more comprehensive understanding of phenomena • Psychology only science which ignores ultimate causation (focus on culture)