Close Relationships I Lecture 15

Moving from Attraction to Close Relationships Evolutionary Perspectives on Mating Evolutionary Perspectives on Mating Need to Belong Need to Belong

Biological Bases of Relationships Reproductive Investment Reproductive Investment Polygamy and Monogamy Polygamy and Monogamy Human Mating Human Mating

Evolutionary Fitness Potential to pass on your genes/successfully procreate Potential to pass on your genes/successfully procreate Ability to survive to mating years Ability to survive to mating years Ability to maximize the number of offspring that survive to their mating years Ability to maximize the number of offspring that survive to their mating years

Reproductive Investment of Each Sex The “investment” of time, resources, and risk involved in having each child The “investment” of time, resources, and risk involved in having each child Typically varies between the sexes Typically varies between the sexes The sex which bears the most reproductive costs is “choosier” The sex which bears the most reproductive costs is “choosier”

Sexual “Choosiness” Choosy Sex Choosy Sex Bears the most reproductive costs/investment Bears the most reproductive costs/investment Usually the female, but not always Usually the female, but not always Sex with least reproductive costs: Sex with least reproductive costs: Should want more partners Should want more partners Will be in competition for mates more often Will be in competition for mates more often Displays greater physical variation Displays greater physical variation

Polygamy Several members of one sex mating with one individual of the other sex Several members of one sex mating with one individual of the other sex Polygyny Polygyny Several females mate with one male Several females mate with one male 90% of mammals 90% of mammals Polyandry Polyandry Several males mate with one female Several males mate with one female

Sexual Dimorphism Pronounced difference in the size or bodily structures of the two sexes Pronounced difference in the size or bodily structures of the two sexes Seen in polygamous animals Seen in polygamous animals

Monogamy Reproductive partnership based on a more or less permanent tie between partners Reproductive partnership based on a more or less permanent tie between partners Sexes are close to indistinguishable based on physical characteristics Sexes are close to indistinguishable based on physical characteristics

Biological Basis of Monogamy Co-occurrence of Oxytocin and Dopamine in Nucleus Accumbens Co-occurrence of Oxytocin and Dopamine in Nucleus Accumbens Dopamine - Reward neurotransmitter Dopamine - Reward neurotransmitter Oxytocin - “Attachment Hormone” that is also a neuropeptide Oxytocin - “Attachment Hormone” that is also a neuropeptide

Biological Basis of Monogamy Monogamous animals Monogamous animals Oxytocin and Dopamine receptors share nucleus accumbens Oxytocin and Dopamine receptors share nucleus accumbens Activation of one activates the other Activation of one activates the other All 5% of monogamous animals share this anatomical feature All 5% of monogamous animals share this anatomical feature Polygamous animals Polygamous animals No oxytocin receptors in nucleus accumbens No oxytocin receptors in nucleus accumbens

Homosexuality Reproductive partnerships between members of the same sex Reproductive partnerships between members of the same sex Wide displayed across the animal kingdom Wide displayed across the animal kingdom Usually associated with disproportionate number of male and female mating adults Usually associated with disproportionate number of male and female mating adults

Human Mating Are we polygamous or monogamous? Are we polygamous or monogamous? Human Mate Selection Human Mate Selection

Are We Polygamous or Monogamous? That’s a tough question That’s a tough question Best thing to do is weigh evidence on both sides... Best thing to do is weigh evidence on both sides...

Polygamous Humans? Polygamy evidence: Polygamy evidence: Sexual dimorphism Sexual dimorphism Great physical variation Great physical variation 85% of traditional cultures allow some kind of polygamy 85% of traditional cultures allow some kind of polygamy

Monogamous Humans? Monogamy evidence: Monogamy evidence: Co-occurence of Oxytocin & Dopamine in human brain Co-occurence of Oxytocin & Dopamine in human brain Great physical variation among both sexes Great physical variation among both sexes 98.9% of men and 99.2% of women report hoping to settle with 1 life partner in the end 98.9% of men and 99.2% of women report hoping to settle with 1 life partner in the end

Polygamous or Monogamous? A A B B

Shades of Grey Evidence that human sexual behaviour changes over lifespan Evidence that human sexual behaviour changes over lifespan Young adulthood Young adulthood Mating tends towards polygamy Mating tends towards polygamy Mid-20s onward Mid-20s onward Mating tends towards monogamy Mating tends towards monogamy Some have argued this is a superior strategy Some have argued this is a superior strategy

Human Mate Selection Evolutionary approaches to mate selection Evolutionary approaches to mate selection Based on reproductive investment models Based on reproductive investment models Assume all behaviour is the product of reproductive fitness Assume all behaviour is the product of reproductive fitness Women have higher reproductive investment Women have higher reproductive investment

Evolutionary Approaches to Mate Selection Given higher reproductive investment for women, evolutionary psych theorists propose … Given higher reproductive investment for women, evolutionary psych theorists propose … Women should desire mates with resources Women should desire mates with resources Men should desire youth and attractiveness more Men should desire youth and attractiveness more

How Important Are Attractiveness & Resources? MenWomen 1. Kind & Understanding 2. Exciting Personality 3. Intelligent 4. Physically Attractive4. Easy Going 5. Healthy 6. Easy Going6. Physically Attractive 7. Wants Children7. Creative 8. Creative8. College Graduate 9. College Graduate9. Good Earning Capacity 10. Good Earning Capacity 10. Wants Children Bus & Barnes (1986)

Are Sex Differences All In the Head (Not in the Act)? Eastwick & Finkel (2008) Eastwick & Finkel (2008) Method: 163 students (81 women, 82 men) Method: 163 students (81 women, 82 men) 1. Participants complete online survey on dating preferences (classic Buss method) 2. Participants participate in 2-hour Speed Dating session

Are Sex Differences All In the Head (Not in the Act)? Eastwick & Finkel (2008) Eastwick & Finkel (2008) Results: Stated preferences (web survey): Results: Stated preferences (web survey): Men rated physical attractiveness as more important Men rated physical attractiveness as more important Women rated earning prospects as more important Women rated earning prospects as more important

Are Sex Differences All In the Head (Not in the Act)? Eastwick & Finkel (2008) Eastwick & Finkel (2008) Results: Actual preferences after Speed Dating Session Results: Actual preferences after Speed Dating Session

Need to Belong Motivation of Belonging Motivation of Belonging Harlow’s Monkeys Harlow’s Monkeys

Need to Belong

Motivation of Belonging Belonging is a basic human motivation Belonging is a basic human motivation Sociometer theory Sociometer theory Human “survival tactics” require several people Human “survival tactics” require several people E.g., building shelters, hunting game, agriculture E.g., building shelters, hunting game, agriculture Human children are helpless for several years Human children are helpless for several years

Need to Belong Compared to those who are isolated from others, people with strong social networks are: Compared to those who are isolated from others, people with strong social networks are: Happier Happier Healthier Healthier Greater life satisfaction Greater life satisfaction

Social Isolation Long-term isolation is a form of official torture/punishment in every society Long-term isolation is a form of official torture/punishment in every society Social ostracism/rejection is an unofficial way to enforce social rules in every society Social ostracism/rejection is an unofficial way to enforce social rules in every society Effects observed in other primates as well Effects observed in other primates as well

Harlow’s Rhesus Monkeys Experiment performed in response to Freud’s Cupboard Theory of caregiver love Experiment performed in response to Freud’s Cupboard Theory of caregiver love Cupboard Theory Cupboard Theory Love of primary caregiver is the result of providing the child with basic needs Love of primary caregiver is the result of providing the child with basic needs Terror of caregiver loss is based on possibility of going unfed Terror of caregiver loss is based on possibility of going unfed Harlow theorized that caregivers were more than food depositories Harlow theorized that caregivers were more than food depositories

Harlow’s Rhesus Monkeys

Where does the monkey turn when frightened?

Harlow’s Rhesus Monkeys

Cloth Mother Present Cloth Mother Absent Exploration high when cloth mother is present, low when cloth mother is absent

What if Monkey Is Socially Isolated? Isolated Rhesus Monkeys Isolated Rhesus Monkeys Socially isolated for 3 months Socially isolated for 3 months Still provided with regular food and “contact comfort” (e.g., good room temperature) Still provided with regular food and “contact comfort” (e.g., good room temperature)

What if Monkey Is Socially Isolated? Dramatic disturbances after 3 months Dramatic disturbances after 3 months Huddling alone, rocking, self-mutilation Huddling alone, rocking, self-mutilation Incompetent (often abusive) parenting Incompetent (often abusive) parenting

What if Monkey is Socially Isolated?

Monkey Therapy Negative impact of isolation could be reduced Negative impact of isolation could be reduced Introduce isolated monkeys to “therapist monkey” Introduce isolated monkeys to “therapist monkey” Therapist Monkey Therapist Monkey Non-isolated, same-age rhesus monkey Non-isolated, same-age rhesus monkey

Monkey Therapy After 2-weeks, isolated monkey will play with therapist monkey After 2-weeks, isolated monkey will play with therapist monkey After ~6 months, isolated monkey seems mostly recovered After ~6 months, isolated monkey seems mostly recovered Remains more easily stressed out than “normal” monkeys Remains more easily stressed out than “normal” monkeys

Example Exam Question According to classic evolutionary approaches to human mate selection, why should monetary resources be more attractive to women than to men? According to classic evolutionary approaches to human mate selection, why should monetary resources be more attractive to women than to men? A. Poverty lowers the survival rate of a child B. Women have a greater need to advance their position in society through wealth C. Money allows for greater time for mating D. Social power is key for parents' survival E. Social status yield greater social opportunities for a child

Example Exam Question According to classic evolutionary approaches to human mate selection, why should monetary resources be more attractive to women than to men? According to classic evolutionary approaches to human mate selection, why should monetary resources be more attractive to women than to men? A. Poverty lowers the survival rate of a child B. Women have a greater need to advance their position in society through wealth C. Money allows for greater time for mating D. Social power is key for parents' survival E. Social status yield greater social opportunities for a child

“Life without love is like a tree without blossoms or fruit.” - Kahlil Gibran Next Time: Next Time: Close Relationships II Close Relationships II Related Websites: Related Websites: Paul Eastwick’s Blog: The Attractionologists Paul Eastwick’s Blog: The Attractionologists attractionologists attractionologists attractionologists attractionologists Harlow demonstrating his research: Harlow demonstrating his research: