- Mutual obligations from both parties, legitimizes sexual contact, stigmatizes EPC (Mate Guarding), indefinite duration.
Common Aspects of Marriage
- Public ritual involving religious authorities - Entitlement of relatives to choose mates and terms - Cohabitation of husband/wife - Explicit trading between relatives for the bride's re/productive output - Relatives also give direct payment for the wife - Less about love, more about getting resources while increasing lineage and obtaining reproductive success - Creates cultural residuals in modern time
Marriage in Humans (also why does conflict in marriage occur?)
- Bi-parental cares causes the relationship between mates to be like that of genetic relatives.
- Their common interests and mutual affection are grounded in correlated fitness Conflict
- Conflict in marriage occurs because fitness goals of each partner don't always line up.
- This is different than strategic interference
- An individual attempts a behaviour that will achieve a fitness goal but is blocked by someone elses
- E.x. Husband may want something that wife doesn't want or will harm them
Ways in which one sex uses strategic inference on another
Imposing fitness costs on the other through: - Deception of intention or mate quality (dressing differently)
- Precluding alternative mating opportunities
- Reduced life expectancy or mate value (Physical damage, death, etc.)
- Parental Investment manipulation (reduced/removal of care in shared offspring or increasing investment in another union)
3 Types of Strategic Interference
1 ) Sexual Over-Perception Bias
- Over estimate the degree of sexually desired and assuming friendliness as sexual intent.
- Due to the lower threshold for mating attempts for men. Because accurate hits are more beneficial than misses are costly, but this means this can be manipulated by female. Or female may be friendly and sexually receptive but not interested in that male.
- Company implemented friendliness training for cashiers, program had to stop because of the amount of sexual harassment complaints from customers that spiked.
2) Commitment Skepticism Bias
- Women are skeptical because males have a lower parental investment and can easily false advertise investment for sex and leave
- Skepticism is good for women for this reason
- 71% Males exaggerate emotional commitment to partner for sex (39% for women)
- 97% of women declare they experienced exaggerated emotional commitment from male partner (59% in men) - this may be because if it's a past partner we always think that
- Women have defences against skepticism bias through asking friends/family and sexual witholding to get more information
3) Sexual Witholding
- "Leading on"
- More destressing for men by making sex more scarse and valuable
- Witholding damages marriages it seems however
Infidelity in LT
- Primary source of conflict in LT
- Has important fitness consequences that are likely to have exerted significant selection pressuresm individuals who have been able to detect and avoid infidelity would have reduced risks to cost
- Each sex has different costs:
Males = cuckoldry (investing in offspring that is not your own)
Females = loss of protection & provisioning
- Infidelity is considered a risky strategy because of retaliation from kin group, devaluation as a quality LT mate by others and STD risk
- Detecting infidelity is very important for males and females to make sure they increase and maintain investments.
- 3 sex differences for infidelity costs (see slide)
Why would women cheat or mate multiply?
- Increase genetic variety (Important because that's basically the reason we have sex)
- Fertility back-up
- Getting additional males to invest, or backup LT mate.
- Transition to a higher mate value partner
- Dual Strategy
- Every male experiences this because we don't gestate the child.
(Why does it exist? What pressure created this in humans? and experiments)
- Jealousy & mate guarding may be solutions to this adaptive problem. Implementation of solutions depend on female fertile and mate value.
- Because of the bridewealth, and cultural practices, women are being treated as a commodity for reproductive success
- Thus, men may try to actively control fidelity and sex in women. To make their FERTILITY a commodity
- Survey questions: What would 1) upset/distress you more 2) difficult to forgive 3) more likely to break up with your partner if they had emotional or sexual intimacy with another.
- Men are more concerned with sexual fidelity because it may signal cuckoldry. Females are more distressed by emotional fidelity because it may signal resource loss.
- Among men who are 100% sure their child is theirs, 2-3% are not.
- Predicts that males will have false positives in suspecting females
(and what does it predict)
- 23% of men, 20% in women (same amounts) - during CURRENT relationship so could be higher
- When males are highly confident in paternity, 2-3% are wrong, low paternity = 30%
- Males are more suspicious of fidelity, but would be more likely to admit infidelity
- Predicts that males will have more false positives when suspecting mates
3 sex differences that fitness costs of infidelity predict
1) Jealousy to Infidelity (Goetz et al., Schutzwohl & Koch)
- Men and women are jealous and concerned with different things that are more costly to them.
2) Parental Attributions (Wilson & Daly 1982, Rhodes, Morly and Simmons)
- It's possible that parental uncertainty in males created pressures where males can assess the likelihood they aren't cuckolded.
3) Mate guarding & retention tactics
- Many behaviours can be considered mate guarding/retaining from love and care to violence
- Various tactics exist and are sex specific
Goetz et al. 2009
- Asked males/females if they will probably cheat on their partner, and if there partner will cheat on them
- Males question/suspect infidelity in their partner more than females but were also more likely to admit that they will commit infidelity themselves.
Infidelity Perception Contingency Table
Partner Actions Target Perceptions
Suspect No Infidelity Suspect Infidelity
No Infidelity Correct Inference False Positive
Infidelity False Negative Correct Inference
- Detecting a partner's sexual infidelity an adaptive problem involving assymetry in the cost of the errors
- Become pregnant from a male who said he will invest, but leaves is extremely costly to the female
Schutzwohl & Koch
- Sex differences in infidelity judgements influence recall by sex in different ways
- Participants read a story about going out to dinner with a person. Some had cues to sexual infidelity (public flirting, etc.), some had emotional cues (doesn't want to go out with you, etc.)
- Person you read about was either a stranger or your romantic partner
- Men recalled sexual infidelity with their partner (high threatening) more, and women emotional.
- No significant difference is less threatening.
Wilson & Daly, 1982
- Looked at baby announcement in newspapers and sent surveys
- Asked who baby looked most similar to.
- Most people say that baby looks like father more than mother (effect is similar but smaller for relatives of parents)
- Could be a protective effect for the offspring.
- For women it would be prudent to reinforce that it looks like the father for increase paternal investment and to protect child from aggression from father if it doesn't look like him.
Rhodes,Morley & Simmons, 2012
(Can we detect infidelity?)
- Faces photographs and survey questions about history of cheating.
- Faces rated on sexual unfaithfulness, untrustworthiness, masc/fem
Female rates: Were only accurate when men's faces were masculine and accurately rated unfaithfulness but not untrustwortihness
- Supports th idea that preceptions of infidelity and untrustworthiness are different things
Male Raters: Incorrectly perceived fem faces as unfaithful
- Overly commit false positives
- Adaptations for detecting fidelity likely only exist for males in long term pair bonds because they aren't concerned with it in ST as women are
Infidelity Detection Hypothesis of Oral Sex
(experiment and theory)
- Theory: About men performing on women only. Recurrent risk of sperm competition may influence likelihood to do these behaviours
- Pham and Shackelford, 2013
- Measured "recurrent risk of sperm competition" by asking questions about the attractiveness of their partner to themselves and other men
- Asked about relationship length and satisfaction as well as last sexual encounter (duration, interest/duration of oral)
Oral sex duration and interest predicted by relationship satisfaction/length, intercourse duration, sperm comp. score
2 other hypothesis for oral sex
(Apply to males/females?)
- Neither applies to males
1) Sperm retention hypothesis: To get females to hold onto more sperm
- Predicts female orgasm because it increases retention.
-Could result in 'competitive advantage', but timing differences of male/femal orasm isn't strongly supported.
2 ) Sexual Satiation Hypothesis: May keep females sexually satisfied so they don't seek EPCs
- Better supported, because sexual dissatisfaction predicts infidelity, and oral sex predicts sexual satisfaction.
(Differences between sexes, and experiments and some examples)
- Women for men: Make-up and clothing (retention, Coolidge effect) and induce jealousy
- Men for women: Conceal partner, threaten rivals, resource displays
- Gangestad, Thornhill, Garver 2002 and Haselton & Gangestad, 2006
- Examples: Violence, vigilance, concealment of mate, monopolization of time, resource display, violence towards rivals, etc.
Gangestad, Thornhill & Garver 2002
- Women in more fertile face more interested in EPC and males are more propreitary and attentive during this time.
Might be cued to signals of higher chance of infidelity
Haselton & Gangestad, 2006
- Got 25 partnered women to track menstrual cycle and rate daily self/other attractiveness, partner's sexual/investment attractiveness, mate's jealousy
- Women who were in relationships with men they found more sexually attractive were less likely to flirt and be attracted to other men in their fertile phase.
- Converse: women with unattracitve partners flirt more and are more attracted to other men
- Women who thought their partner was more investment than sexually attractive were more flirty (could reflect dual stage mating strategy).
- Men with less attractive partners are more jealous and possessive during their fertile phase
- Because they may allocate resources. Men with attractive partners are always mate guarding because threat is always high
Violence Towards Partner
- Women are always at an increased risk but a lot more in a spousal relationship
- A "coercive tactic of proprietary men"
- Letal/non lethal
- Attempt to restrict autonomy
- Many costs: Raises victims incentives to leave and risks retribution.
- Females of relationships are significantly the victim in every type of incident in Canada across all ages
- Female spouses are more likely to be aggressed on but the effect is not significant for dating relationship from either male condition (see slide 53)
- Married women are more likely to be killed by husband they are separated than while co-residing
(Stats and experiments)
- Women more often the target of sexual harrassment. Targets are usually young, attractive and single.
- More distressing to women: if co-worker asked for sex, 63% vs. 15% women/men would be insulted, 17%/67% would be flattered
- Bus 2003. How upset (1-7) if unknown man persisted in asking for sex despire refusals: Less insulted if male is higher status
- Buss 1989: Asked how upset they would be at sexual aggression, and the negative impact of sexual aggression on other
- 6.5 f vs 3.02m upset, 5.8f vs 6.5m impact
- Men underestimate the impact of sexually aggression and get less upset if it happens to them (which makes sense)
- Rape is also considered sexual coercision (see card)
2 Evolutionary Theories about Rape
1) Rape as an adaptation
- Selection favoured males who raped in certain circumstances
- Not supported because: women who were the victims of rape may not keep offspring, suffers health consequence. Not likely to increase in subsequent generations due to costs for both sexes
2) Rape as a by-product
- Rape is maladaptive by-product of evolved male psychology.
- Because of things like sexual overperception bias. They are getting more false-positives to sexual interest and other things
Female Psychological Adaptations Against Sexual Coercion
(3 of them and examples)
1) Pre-ovulatory risk avoidance: women go out to bars and other events to seek mating opportunities at highest fertility, but will go with a group of other women in a coalitionary form.
2) Bodyguard Hypothesis: May prefer larger more m men as a form of protection.
3) Development of specialized fears: Women are more afraid of being raped when they are young as opposed to old, and less as they get older.
- More afraid about robbery/burglary at older ages, not rape.
Benefits of Marriage
(men and women)
Men gain: exlusive sexual access, increased parternal certainty, increased fidelity from female
- Also predicts increased offspring quality and survival if father was co-resident.
-Due to consistent long term support, men who who live with their offspring invest more than if separated.
Women gain: protection and provisioning for self and offspring.
Marriage and Conflict Summary
(and exaples for the 3 types of sex differences)
- Sexual conflict stemsp from strategic interference
- Sex differences in responses to infidelity