Evolution and Human Behavior <ul><li>Sociobiology: The New Synthesis (1975) by E. O. Wilson </li></ul><ul><li>A total of 2...
Misunderstandings About Sociobiology <ul><li>Human beings are not concerned about inclusive fitness: We often don’t know w...
Evolutionary Psychology  <ul><li>Assume the mind is “modular” made up of specialized circuits </li></ul><ul><li>Designed t...
Wason Selection Task <ul><li>You are the new file clerk at the local high school. You must verify that documents conform t...
Wason Selection Task <ul><li>You are the bouncer at a bar.  You need to be sure that the law is not being broken.  If a pe...
Logical Structure is the same <ul><li>If  P  then  Q. </li></ul><ul><li>Logically the rule for testing the truth involves ...
Arbitrary Culture Theory <ul><li>In opposition to evolutionary explanations of human behavior </li></ul><ul><li>Claims tha...
Evolutionary Explanation of Adoption <ul><li>Adoption should be frequent when adopted children are related to the adopting...
 
Proximate Mechanisms for Adoption <ul><li>Parental “instincts” are aroused for childless couples </li></ul><ul><li>Inabili...
 
What Do We Want in a Mate? <ul><li>From the standpoint of fitness, we want successful offspring </li></ul><ul><li>Males wa...
Male Mate Preferences <ul><li>Youth: Females maximum fecundity is at about 26 years old </li></ul><ul><li>Waste-to-hip rat...
 
Mate Preferences and Ovulatory Cycle <ul><li>Humans females are supposed to be “Concealed Ovulaters” giving no sign of the...
More on Ovulation Cycle <ul><li>Women show more skin and touch men more during their fertile period </li></ul><ul><li>Wome...
Female Mate Preferences <ul><li>Men who have resources: Professional, good job, educated </li></ul><ul><li>Men who are old...
Masculine Faces <ul><li>Testosterone levels during development correlate with masculinized face </li></ul><ul><li>High tes...
 
 
Income and Earning Power <ul><li>Data from surveys show females rate earning potential much higher than males, across 37 c...
 
Mate Preferences for Both Sexes <ul><li>Kind and Considerate </li></ul><ul><li>Good sense of humor </li></ul><ul><li>Symme...
Conditional Mate Preferences <ul><li>Self rated attractiveness is positively correlated with preference for attractiveness...
 
Conditional Preferences <ul><li>Minimum acceptable intelligence for different levels of involvement (50% means at the midd...
Clark and Hatfield Study <ul><li>Had an attractive male or female experimenter approach a member of the opposite sex </li>...
Number of Partners <ul><li>Males desire more partners in their lifetime than do females </li></ul><ul><li>Males would enga...
 
 
Jealousy <ul><li>Males are concerned with paternity of offspring </li></ul><ul><li>Females are concerned with help raising...
Which is more upsetting? <ul><li>Imagine yourself in a committed relationship and your partner becomes involved with anoth...
Which is more upsetting? <ul><li>Imagine the same committed relationship, but now your partner becomes involved with a per...
Results <ul><li>Heterosexual relationship: Males say sex 60%, females say sex 30% </li></ul><ul><li>Homosexual relationshi...
Sex Differences in Spatial Abilities <ul><li>Division of labor: Hunters and gatherers </li></ul><ul><li>To be a good hunte...
 
Human Conditional Mating Strategies <ul><li>Recall conditional strategy of the scorpionfly: guard insect, produce saliva, ...
Characteristics of Rape <ul><li>Females are more likely to become pregnant by rape than by consensual sex </li></ul><ul><l...
 
Rape as a maladaptive side effect <ul><li>Male’s motivation for many sexual partners and quick sexual arousal lead to over...
Parental Care <ul><li>Certainty of parenthood affects amount of parental (grand parent) investment </li></ul><ul><li>How m...
% Students ranking each grandparent as most invested
Parental Resource Allocation <ul><li>Males must often compete for limited number of females </li></ul><ul><li>Bridewealth ...
Inheritance <ul><li>Sons receive more inheritance from parents that daughters, particularly in polygynous cultures </li></...
<ul><li>Increased wealth increases the proportion of inheritance given to sons </li></ul><ul><li>High levels of wealth inc...
 
Biological vs. Non-Biological Parents <ul><li>Step children are usually not given as much parental investment as biologica...
 
<ul><li>Step children are more at risk for child abuse than biological children </li></ul><ul><li>Daly and Wilson data sho...
 
Stone-age Mind in a Modern Society <ul><li>Many problems with today’s world may have been adaptations that were successful...
<ul><li>Cooperation in hunting and other tasks = in-group—out-group mentality </li></ul><ul><li>My group is good, the othe...
 
The Future <ul><li>E. O. Wilson claimed in his book,  Sociobiology: The New Synthesis  in 1975 that evolutionary theory wo...
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Evolve 7

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Evolve 7

  1. 1. Evolution and Human Behavior <ul><li>Sociobiology: The New Synthesis (1975) by E. O. Wilson </li></ul><ul><li>A total of 26 chapters, the last one on human beings </li></ul><ul><li>Controversy followed: Culture vs Biology </li></ul>
  2. 2. Misunderstandings About Sociobiology <ul><li>Human beings are not concerned about inclusive fitness: We often don’t know what motivates us, like food preferences and mate preferences </li></ul><ul><li>Much of human behavior is not adaptive: The concept of the Environment of Evolutionary Adaptation (EEA) </li></ul><ul><li>Sociobiology is a justification of racism and elitism: Confuse what is with what should be </li></ul>
  3. 3. Evolutionary Psychology <ul><li>Assume the mind is “modular” made up of specialized circuits </li></ul><ul><li>Designed to solve re-occurring problems from the EEA </li></ul><ul><li>Domain specific </li></ul><ul><li>Analogy to a Swiss Army knife </li></ul>
  4. 4. Wason Selection Task <ul><li>You are the new file clerk at the local high school. You must verify that documents conform to a certain rule. The rule is: </li></ul><ul><li>If a person has a “D” rating, then his documents must be marked code “3”. </li></ul><ul><li>Which of the following do you need to see additional information? 1. “D” 2. “F” 3. “3” 4. “7” </li></ul>
  5. 5. Wason Selection Task <ul><li>You are the bouncer at a bar. You need to be sure that the law is not being broken. If a person is drinking beer, the he must be over 21 years old. Which of the following do you need to see additional information? </li></ul><ul><li>1. drinking beer 2. drinking coke 3. 25 years old 4. 16 years old </li></ul>
  6. 6. Logical Structure is the same <ul><li>If P then Q. </li></ul><ul><li>Logically the rule for testing the truth involves P and not- Q. </li></ul><ul><li>The content makes it easy for the beer drinking example, much harder for the file clerk example </li></ul><ul><li>The brain is specialized to detect cheaters in social interactions. </li></ul>
  7. 7. Arbitrary Culture Theory <ul><li>In opposition to evolutionary explanations of human behavior </li></ul><ul><li>Claims that most behavior is a reflection of traditions and unique customs of a particular people </li></ul><ul><li>Example: High rates of adoption in the islands in the central Pacific ocean </li></ul>
  8. 8. Evolutionary Explanation of Adoption <ul><li>Adoption should be frequent when adopted children are related to the adopting parents </li></ul>
  9. 10. Proximate Mechanisms for Adoption <ul><li>Parental “instincts” are aroused for childless couples </li></ul><ul><li>Inability to have children is most frequently given reason for seeking adoption </li></ul><ul><li>In the EEA infertile women would likely be living with close relatives making “adoption” adaptive </li></ul><ul><li>Many childless women and couple treat pets (usually dogs) like children </li></ul>
  10. 12. What Do We Want in a Mate? <ul><li>From the standpoint of fitness, we want successful offspring </li></ul><ul><li>Males want a female who will become pregnant and have a healthy baby </li></ul><ul><li>Women want men who will help raise the offspring </li></ul>
  11. 13. Male Mate Preferences <ul><li>Youth: Females maximum fecundity is at about 26 years old </li></ul><ul><li>Waste-to-hip ratio of .7: Also an honest marker of fertility and health </li></ul><ul><li>Narrow waist, large breasts: Also correlated with fertility </li></ul>
  12. 15. Mate Preferences and Ovulatory Cycle <ul><li>Humans females are supposed to be “Concealed Ovulaters” giving no sign of their fertile period </li></ul><ul><li>Tee shirt studies show that males prefer the smell of ovulating women over non-ovulating </li></ul><ul><li>Males rate faces of ovulating women as being more attractive </li></ul>
  13. 16. More on Ovulation Cycle <ul><li>Women show more skin and touch men more during their fertile period </li></ul><ul><li>Women prefer a masculinized male face during their fertile period and non-masculinized otherwise </li></ul><ul><li>Paradoxically, women rate their own attractiveness lower during their fertile period </li></ul>
  14. 17. Female Mate Preferences <ul><li>Men who have resources: Professional, good job, educated </li></ul><ul><li>Men who are older </li></ul><ul><li>Men who are high in status </li></ul><ul><li>Men who are athletic </li></ul><ul><li>Men who have masculine faces (testosterone correlated) </li></ul>
  15. 18. Masculine Faces <ul><li>Testosterone levels during development correlate with masculinized face </li></ul><ul><li>High testosterone may also signal a strong immune system </li></ul><ul><li>Testosterone has a pleitropic effect: High levels early in life may shorten life span </li></ul><ul><li>Increasing masculinity from left to right in next slide </li></ul>
  16. 21. Income and Earning Power <ul><li>Data from surveys show females rate earning potential much higher than males, across 37 countries (David Buss) </li></ul><ul><li>Data from “Man seeking woman” and “Woman seeking man” ads also confirm the difference </li></ul>
  17. 23. Mate Preferences for Both Sexes <ul><li>Kind and Considerate </li></ul><ul><li>Good sense of humor </li></ul><ul><li>Symmetry of face and body: A marker of good developmental homeostasis </li></ul>
  18. 24. Conditional Mate Preferences <ul><li>Self rated attractiveness is positively correlated with preference for attractiveness in a mate </li></ul>
  19. 26. Conditional Preferences <ul><li>Minimum acceptable intelligence for different levels of involvement (50% means at the middle of the intelligence scale for the population </li></ul>
  20. 27. Clark and Hatfield Study <ul><li>Had an attractive male or female experimenter approach a member of the opposite sex </li></ul><ul><li>Experimenter ask the stranger, would you like to go out with me?, or would you like to come to my apartment tonight? Or would you sleep with me tonight? </li></ul><ul><li>Females: 50%, 10%, 0% said yes </li></ul><ul><li>Males: 50%, 60%, 65% said yes </li></ul>
  21. 28. Number of Partners <ul><li>Males desire more partners in their lifetime than do females </li></ul><ul><li>Males would engage in sex sooner in the relationship than females </li></ul>
  22. 31. Jealousy <ul><li>Males are concerned with paternity of offspring </li></ul><ul><li>Females are concerned with help raising offspring </li></ul><ul><li>Threats to these characteristics give rise to jealousy—becoming upset </li></ul>
  23. 32. Which is more upsetting? <ul><li>Imagine yourself in a committed relationship and your partner becomes involved with another person. Which is more upsetting? </li></ul><ul><li>You partner has a passionate sexual relationship with that person </li></ul><ul><li>Your partner has formed a deep emotional bond with that person </li></ul>
  24. 33. Which is more upsetting? <ul><li>Imagine the same committed relationship, but now your partner becomes involved with a person of the same sex as your partner. Which is more upsetting? </li></ul><ul><li>You partner has a passionate sexual relationship with that person </li></ul><ul><li>Your partner has formed a deep emotional bond with that person </li></ul>
  25. 34. Results <ul><li>Heterosexual relationship: Males say sex 60%, females say sex 30% </li></ul><ul><li>Homosexual relationship: Males say sex 50%, females say sex 80% </li></ul>
  26. 35. Sex Differences in Spatial Abilities <ul><li>Division of labor: Hunters and gatherers </li></ul><ul><li>To be a good hunter must be able to keep track of where the prey is, where home is and how to get there: Spatial rotation task. </li></ul><ul><li>To be a good gatherer must remember where food was located: Plants don’t move around. Spatial memory task </li></ul>
  27. 37. Human Conditional Mating Strategies <ul><li>Recall conditional strategy of the scorpionfly: guard insect, produce saliva, forced copulation </li></ul><ul><li>Is human rape a conditional mating strategy? Or is it males way for controlling females by fear? </li></ul>
  28. 38. Characteristics of Rape <ul><li>Females are more likely to become pregnant by rape than by consensual sex </li></ul><ul><li>If rape is an adaptation, then most fertile women should be most often raped </li></ul><ul><li>If rape is male intimidation, then it should be most frequent in women who are in powerful positions, and should be comparable to murder </li></ul>
  29. 40. Rape as a maladaptive side effect <ul><li>Male’s motivation for many sexual partners and quick sexual arousal lead to over-expression of sexual behavior </li></ul><ul><li>Predicts that rapists should have more consensual sex than average, which is supported by some data </li></ul><ul><li>Final explanation of why rape occurs is not done </li></ul>
  30. 41. Parental Care <ul><li>Certainty of parenthood affects amount of parental (grand parent) investment </li></ul><ul><li>How much support have you received from your grandparents? </li></ul><ul><li>Mother’s mother has greatest certainty of parenthood, father’s father the least certainty, and father’s mother and mother’s farther are intermediate </li></ul>
  31. 42. % Students ranking each grandparent as most invested
  32. 43. Parental Resource Allocation <ul><li>Males must often compete for limited number of females </li></ul><ul><li>Bridewealth is male giving resources to females family </li></ul><ul><li>Dowry is female giving resources to males family </li></ul><ul><li>Bridewealth is much more common, particularly in polygynous cultures </li></ul>
  33. 44. Inheritance <ul><li>Sons receive more inheritance from parents that daughters, particularly in polygynous cultures </li></ul><ul><li>In monogamous cultures, sons are favored 58% of the time </li></ul><ul><li>In polygynous cultures, sons are favored 80 to 97% of the time </li></ul>
  34. 45. <ul><li>Increased wealth increases the proportion of inheritance given to sons </li></ul><ul><li>High levels of wealth increase a males chances of successful reproduction </li></ul><ul><li>Data from Canada: </li></ul>
  35. 47. Biological vs. Non-Biological Parents <ul><li>Step children are usually not given as much parental investment as biological children </li></ul><ul><li>Giving a child money to help attend college: </li></ul>
  36. 49. <ul><li>Step children are more at risk for child abuse than biological children </li></ul><ul><li>Daly and Wilson data show that step child is 100 times more likely to be killed than biological child </li></ul><ul><li>Child abused is also higher in stepchildren, especially young ones </li></ul>
  37. 51. Stone-age Mind in a Modern Society <ul><li>Many problems with today’s world may have been adaptations that were successful in our evolutionary past </li></ul><ul><li>Eating sweet and calorically rich foods=obesity </li></ul><ul><li>Oportunistically using resources = deforestation, overfarming,overfishing </li></ul><ul><li>Producing tools and artifacts quickly and efficiently = pollution </li></ul>
  38. 52. <ul><li>Cooperation in hunting and other tasks = in-group—out-group mentality </li></ul><ul><li>My group is good, the other groups I meet are not </li></ul><ul><li>Ability to acquire information from experience = “bad” information is as easy to acquire as good. </li></ul><ul><li>Chimps hunt in groups and return home after the hunt </li></ul>
  39. 54. The Future <ul><li>E. O. Wilson claimed in his book, Sociobiology: The New Synthesis in 1975 that evolutionary theory would transform the social and behavioral sciences </li></ul><ul><li>Was he right? </li></ul>

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