9.00 Introduction to Psychology Prof. Steven Pinker Week 3, Lecture 1: Evolution and Psychology Evolution of the Mind and Brain • Why does the brain work the way it does? • Reverse-engineering. • Reverse-engineer bodies. • Paley’s problem: Complex adaptive design. One possible explanation of Darwin’s Theory of Natural complex design: Selection • Creationism • Another explanation of complex design • Some problems with creationism: • Components of the theory: – Pushes back the question. – 1. Replication – Continuity of brain & behavior with animals – 2. Competition for resources – Vestigial characters: anatomical and – 3. Copying errors behavioral. – 4. Differential replication – Fossil record. – 5. Appearance of design 1 9.00 Introduction to Psychology Prof. Steven Pinker Week 3, Lecture 1: Evolution and Psychology Can Natural Selection Really Natural Selection ¹ Progress “Design” Complex Behavior? • “The Ascent of Man” 2 9.00 Introduction to Psychology Prof. Steven Pinker Week 3, Lecture 1: Evolution and Psychology Human Cognition and Emotion Not Everything is Adaptive as Adaptations • Adaptations versus by-products. • Evolution as an arms race • How to tell by-products from adaptations: • Homo sapiens and the “cognitive niche” • Some psychological adaptations: – Improbable, complex design – Color vision – Intuitive physics – Fear of heights • Some by-products? – Dreams? – Art? 3 9.00 Introduction to Psychology Prof. Steven Pinker Week 3, Lecture 1: Evolution and Psychology The Timetable of The Timetable of Human Evolution Human Evolution, continued • Some important dates: • Modern Homo sapiens: 200,000 – 70,000 – Chimp -human split: 6-8 million years ago years ago – First Australopithecines (“Lucy”) ~4 million • Exit from Africa and divergence of “races”: years ago 100,000 – 50,000 years ago – Homo habilis (“Handyman”): 2 million years • Agricultural revolution: beginning ~ 10,000 ago years ago – Homo erectus (“Peking/Java Man”): 1 million years ago Environment of Evolutionary Environment of Evolutionary Adaptedness Adaptedness, continued • Before the agricultural revolution, humans • Predictions for innate psychological lived a hunter-gatherer (forager) lifestyle: modules: spoken language versus reading. – Small bands, mostly nomadic. • Predictions for biological non-adaptiveness – No stored food, government, law, strangers, of modern behavior permanent dwellings, social stratification, – Junk food inequality of wealth, armies, written language, – Contraception formal science & education, … – Drugs 4 9.00 Introduction to Psychology Prof. Steven Pinker Week 3, Lecture 1: Evolution and Psychology An Example of Evolutionary Evidence that Pregnancy Psychology: Pregnancy Sickness Sickness is an Adaptation: • Many non-toxic plant compounds are • The phenomenon. teratogenic • Freudian explanation. • Onset coincides with structure-building, • Margie Profet’s Hypothesis: Prevents slow growth of embryo women from ingesting teratogens. • Offset continues with completion of • Need for independent evidence (signs of structure, rapid growth of fetus “engineering design”). • Avoided foods are higher in toxins Evidence that Pregnancy Sickness is an Adaptation, cont. • Hypersensitivity of smell • Wild plants are higher in toxins • Cross-cultural universality • Negative correlation between pregnancy sickness and miscarriage • Negative correlation between pregnancy sickness and birth defects 5.