Sexual Conflict: Outline

Evolutionary psychology predicts differences between the sexual strategies favored by females and males, leading to conflicts of interest.

Outline

I Sexually-antagonistic selection

I Sources of conflict between men and women

I Communication biases: sexy or friendly?

I

I Sexual conflict in non-humans What is this? The Ruddy Duck and its penis

(from Patricia Brennan) A genital arms race: Antagonistic co-evolution Sexual conflict in Dunnocks Sperm competition and sexual conflict in fruitflies

Fruitfly sperm is toxic to other sperm: 1. sexual selection (sperm competition) favors increasingly toxic sperm 2. but harmful to females (reduces their lifespan)

William Rice’s experiments (reserve reading) 1. He prevented females from evolving a response: What happened? 2. Suppressed male-male competition through : What happened? Genomic imprinting as sexual confict

Imprinted genes: genes that are are silenced (not expressed) when they come from one sex or the other

Some maternal genes slow down growth, paternal genes favor it.

Why? Sources of conflict between men and women

Buss asked undergraduates what it is about men that infuriates women, and vice versa

Female complaints?

I Sexual , sexual harrassment

I Lack of commitment

I Doesn’t express his feelings openly Male complaints?

I Sexual withholding

I She wants to monopolize his time (commitment) Communication biases: Sexy or friendly?

Are they flirting? Or just being friendly?

Men more likely than women to assume sexual intent Jealousy What are men and women jealous about?

Buss study: Imagine that you discover that the person with whom you’ve been seriously involved became interested in someone else.

What would distres or upset you more:

I imagining your partner forming a deep emotional attachment to that person

I imagining your partner enjoying passionate sexual intercourse with that other person What are men and women jealous about?

I 60% of males were more upset by sexual infidelity

I 83% of women more upset by emotional investment in rival

I Result replicated with physiological measures

I Supported by a recent (2012) meta-analysis of 45 studies. Sexual Jealousy: Cross-cultural differences

Himba (pastoralists) and Tchimba (foragers, few cattle)

I little male investment (matrilineal inheritance)

I lots of extra-pair paternity

I women: little concern over emotional jealousy

I men: no concern over emotional jealousy

I no sex difference among the Tchimba Sexual jealousy: Abuse and homicide

Homicide between romantic partners is overwhelmingly about sexual jealousy:

I Canada: 25% of 800 cases, motive was “jealousy” (many others related, e.g., “pays too much attention to other men” )

I in-depth study, 31 men who killed wives: 81% over sexual proprietariness (most after she left for new partner)

I where women kill men, usually follows his to her.

Not adaptive, but an extreme expression of male sexual jealousy

(from Daly and Wilson, 1988) Mate guarding, abuse and homicide Risk of wife-killing (uxoricide) is much higher immediately after separation

Killing is spiteful, not adaptive. But threats lose credibility if the actor is seen to be bluffing. (Wilson and Daiy, 1998) Is there a sex difference in spouse abuse?

Studies using “Conflict Tactics Scale” (CTS) finds no sex difference

Some critiques:

I CTS about behaviors used to resolve conflicts, ignores who initiates, motive, severity

I poor agreement between husbands and wives on the scale Johnson (2006) distinguishes

I intimate terrorism (violence involving proprietariness and control)

I situational couple violence (from conflicts of daily life)

Intimate terrorism causes more harm Rape: Who ? Do men rape because they lack other options? No (at least not in college students)

sexual experience: NE (none), NCE (noncoercive), NPCE (non-physical coercive), PCE (physical coercive) (from Lalumiere et al. 1996) Rape: Who rapes?

Personality differences: Men who rape more likely to have

I short-term uncommitted attitudes to romantic relationships

I more likely to interpret hostile rejection as

I more difficulty reading womens’ negative, but not positive, cues

I for a subset of men, associated with hostile masculinity, lack of empathy Rape: Evolutionary perspectives

Is rape about sex or power? Or both? Age distribution of rape victims reflects age distribution of women’s reproductive value (vs. age distribution of assault)

Is it a specific adaptation? or byproduct of men’s mating psychology? Latter position argues not an adaptation per se, but an outcome of male mating psychology; men sometimes use force to get what they want, especially where the costs are low:

I warfare

I women without familial or other support

I high-status men unlikely to face sanctions Summary

I Sexually-antagonistic selection can produce a costly evolutionary arms race (antagonistic co-evolution)

I Monogamy (at least in fruitflies) reduces costs and conflict, aligns the interests of males and females

I Much of the conflict between men and women reflects differences in sexual strategies

I Men biased to see sexual intent in an interaction women see as friendly.

I Infidelity bothers both men and women, but jealousy is stronger for sexual infidelity in men, emotional infidelity in women. Former signals loss of paternity, latter loss of investment

I Mate guarding: Jealousy and sexual proprietariness are key motives for spousal homicide