The New Science of Evolutionary Psychology

1. The New Science of Evolutionary Psychology Chapter 2

2. Three Theories for The Origins of Adaptations • Creationism • Seeding theory • Evolution by natural selection • Which of the theories is scientific and why?

3. The Three Products of Evolution • Adaptations • By-products • Noise

4. What is an Adaptation? • An inherited and reliably developing characteristic that came into to existence through natural selection because it helped to solve a problem of survival or reproduction during the period of its evolution • Must show evidence of special design • Must show evidence it improves fitness

5. The Environment of Evolutionary Adaptedness (EEA) • The adaptive problems or selection forces that were responsible for shaping the adaptation over deep evolutionary time • Not a time period, but a set of circumstances • Each adaptation has its own EEA

6. Byproducts • Characteristics that do not solve design problems and do not have functional design • Come along with adaptations

7. Noise • Random effects • May harm the organism or be neutral ________________________________ The female orgasm: Adaptation, by-product, or noise?

8. Levels of Evolutionary Analysis General Evolutionary Theory (Darwin) Middle Level Theories: Parental Investment Theory (Trivers) Specific Evolutionary Hypotheses: In species where males contribute resources to offspring, females will seek males who are willing and able to do so Specific Predictions Based on Hypothesis: Women prefer men who show generosity during courtship

9. Strategies for Generating and Testing Hypotheses Theory Driven Parental Investment Theory Develop and Test Hypothesis: collect observations of women’s responses to personal ads that vary with regard to stated income Observation Driven Develop and Test Hypothesis: collect observations of women’s responses to personal ads that vary with regard to stated income Observation: women seem to prefer men who have higher incomes

10. Human Nature • All species have a nature that evolved through natural selection • All psychological theories are evolutionary- all contain premises about human nature • The human mind has evolved psychological mechanisms to solve adaptive problems

11. What is a Mechanism? • Example: Callous producing mechanism • Physical processes that cause toughening of the skin in response to specific environmental inputs • Solves a specific problem • Is a universal mechanism but the output will vary based on experience

12. Evolved Psychological Mechanisms: Definition • Exists because it evolved as an adaptation • Designed to process specific, limited input • Input has information value to the organism about what adaptive problem it is facing • Input takes form of decision rules (if-then) • Output: physiological response, communication to other mechanisms, or overt behavior • Output of mechanism is directed at solving a particular adaptive problem

13. Properties of Evolved Psychological Mechanisms • The mind is “carved at its joints” based on function, although functions are coordinated • Mechanisms are problem- specificand numerous • Mechanisms are not rigid instincts but allow behavioral flexibility • Are activated by specific environmental inputs • Involve decision rules that permit multiple options

14. Evolution and Culture • Evolution and learning are not opposites • Learning and culture are descriptions for how environmental inputs interacts with psychological mechanisms • Culture is a description that requires explanation- it is not an explanation by itself

15. Culture

16. Methods for Testing Hypotheses • Comparing species • Comparing males and females • Comparing individuals within species • Comparing individual across contexts • Experimental methods

17. Data Sources for Testing Hypotheses • Archaeological records • Data from hunter gatherer societies • Observations • Self-reports • Life history data and public records • Human products * Multiple data sources allow evidence to converge

18. Identifying Adaptive Problems Guideline 1: Modern Evolutionary Theory • Problems of survival and growth • Problems of mating • Problems of parenting • Problems of assisting genetic relatives

19. Guideline 2: Knowledge of Universal Human Structures • Identifying common features of human experience provides a starting place for likely adaptive problems (e.g. Brown’s Human Universals) • Social hierarchies • Giving birth in presence of others

20. Guideline 3: Traditional Societies • Hunter-gatherer groups more closely resemble the conditions under which humans evolved • Humans were hunter-gatherers for 99% of our history

21. Guideline 4: Paleoarchaeology and Paleoanthropology • Analysis of fossils and tools allows a window into adaptive problems that our ancestors faced

22. Guideline 5: Current Psychological Mechanisms • Fear of snakes • Taste aversions • Sexual jealousy

23. Guideline 6: Task Analysis • Analyze an observation into the various behavioral and cognitive tasks necessary for it to occur • Observation: humans generally avoid sexual contact with closely related kin