Transcript Chapter 7: Primate Mating Systems

Chapter 7: Primate Mating Systems
•Mating Systems are patterns of
reproductive strategies between
females and males within a species.
–Mating effort: finding a mate, bonding
between sexes (monogamy, polygyny,
polyandry, harems, multi-sex, etc.,)
–Parenting effort: caring and provisioning
of offspring (mother only, mother and
father, alloparental care or cooperative
breeding)
Behavioral Adaptations or Strategies
• Strategies:
– are behavioral adaptations (designed by
natural selection to solve ESP).
– weigh the cost and benefits of alternative
behaviors that address the same functional
problem (of opportunity).
– Mating strategies are reproductive
adaptations
Trivers’ Parental Investment Theory:
1. The sex who invests most will be most
selective in mate choice: inter-sexual
selection
2. The sex who invests the least will be more
competitive for sexual access: intra-sexual
selection
– Go to a bar . . .
– Peacock tails and the power of female mate
choice: inter-sexual selection.
– Better providers and sexier sons
Big-Mama theory and Seahorses
What criteria do Women use in
choosing a long term mate?
Wealth:
ability to
invest
• Dragonfly love
• Future earning power
• Generosity: willingness to invest in
wife in kids
• Economic fidelity
• Protection: size, bravery and skill
– Predators
– Other men
– Holding on to resources
• Technological skills
Status
• More resources and able to hold on to
resources
• Political and physical protection
• Higher status children
• Power is the ultimate aphrodisiac and the
Hill-Side Strangler
• Hypogamy
• Cultural and environmental standards for
success criteria
• Dilbert and Computer Nerds
• Physical size
• Age is a proxy for wealth and power
• Cultural differences
• Good father
– Teach skills to sons
– Help teach daughters to recognize high quality
males
• Potential
– James Dean and rebels without a cause
– Ambition vs. laziness
• Can’t trust a flake!
– Undependable
– Emotionally unstable or immature
– Less likely to bet the family fortune on a football
game
– Less likely to be insecure and physically abusive
– Less likely to leave them for another woman.
• Athletic Prowess offers cues to:
– Ability to acquire resources
– Protection
– Status
– Taller men:
• Earn more money
• Win elections
• More attractive
Symmetry
•Better able to invest
•Healthier children
• Men with babies, dogs, other women:
cues of willingness to invest
• Women with money: “structural
powerlessness hypothesis”
– Not just “wealthy powerful men are more
attractive,” but a thermostatic like
mechanism for “cutting the best deal”
– What about Madonna?
– Becker’s divorce rate study
Husbands vs. Studs
• Good behavioral traits over good looks
for husbands
• Women in long-term relationships more
likely to go for good traits
What do Men Look for in a Long-term Mate?
• Guinness Book of Records: Moulay Ismail the
Bloodthirsty (1672-1727), emperor of Morocco was
reported to have killed 30,000 people with his own
hands, and had 888 children, 4 wives and a harem of
500 concubines. His senior wife managed the harem
for him. Each concubine had her own eunuch and a
personal female slave. They were forbidden to visit
even among themselves and when one Westerner
was visiting the emperor 14 concubines who had
been caught visiting each other had all of their teeth
pulled out as punishment. They were shipped out to
an underling’s harem when they turned 30.
• Precolonial kingdoms of Africa: the Ashanti,
Azande, Baganda, and Zulu Kings are
reported to have had harems of over a
thousand women, so too did harems in India,
China and in the Muslim world.
• Chinese imperial harems of a thousand
women had well managed copulation
schedules on a rotating basis according to
menstrual cycle.
• In the early 1900’s an Indian potentate was
reported to have had 4 children born in 8
days with 9 more due the following week.
• This kind of power is very recent in evolutionary time
and could not have led to evolved psychological
mechanisms.
– Yes but:
– Demonstrates evolved male desires.
– Men with unleashed power can do what they want and this
is what they want.
• Powerful men in tribal societies may not have had
the opportunity to have sexual access to thousands
of women, but many had two, three, four and more
times the number of wives than did less powerful
men.
– e.g., Shinbone, Yanomamö head man and renown warrior
had 11wives, 43 children, 231 grandchildren, and 480 greatgrandchildren with more to come.
– Wilt Chamberlain, and Magic Johnson?
– Year of the documentary at Sundance
• Women seek men who commit or at least can
convince them that they are committed.
• In the past men who would not commit or
cheated would be well known, modern
societies allow for more anonymity.
• Men who were in committed relationships
had:
– Greater paternal certainty.
– Children with greater survival rates.
• Prediction: in environments with lower childhood
mortality (richer environments) more men will pursue a
short-term strategy, i.e., less committed, cheat.
– Greater chance of marrying well
– Children with a greater chance of marrying well
If men are going to commit they
should also be choosy
• “Beauty is in the adaptations of the
beholder” (Symons)
• Universal standards of beauty
• Preference for beauty in infants (presocialized children)
• Unlike other primates, women are
hyper-sexually attractive
• Men are attracted to woman who show
cues of greater fertility
– Cues of health
– Skin tone and complexion
– Cultural differences in skin color
– Clear eyes
– Healthy hair
– Symmetry
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Cues of youth
– “Hey nine-teen” (Steely Dan)
– Neotonous features
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Smaller lower face
High check bones
Smaller jaw
Bigger eyes
Smaller mouth with fuller lips
– Anti-gravity
– High check bones again
– Lack of sagging skin and body parts (bras)
• Average features
• Hip-Waist ratios
• Cues of ovulation
– Good for short term mating but more
complicated when also calculating in
commitment
– Lighter skin
– Rosy cheeks
• Also smells (“The Scent of Eros”)
• Makeup mimics cues of health, youth, and
ovulation.
• Behaviors that are attractive
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Cues of youth, health, and ovulation
Cues of paternal certainty
Virgins (sex differences in preference)
Cultural differences
Sluts
Controllable?
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Smaller
Naive or flaky
Not assertive
Earn less money?
In short: “Men want physically
attractive, young, sexually loyal
wives who will remain faithful
until death.”
Short-Term Sexual Strategies
• The benefits to men are clear, but what are
the costs?
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STDs
Risk of losing long-term partner
Lower one’s opportunity for marriage
Lower chance of attracting a high quality mate
Wife my leave you or have affairs
Revenge
Risk management
Increase mortality of one’s children
Richer environments would favor short-term
matings
• Wealth/Status effects on benefits
• Violence
– From husband
– From women’s kinspeople
– From your kinspeople
– From wife
– A well deserved reputation for fierceness
will favor short-term matings
– Loss of alliances
– Women’s kin mad
– Your kin
What are the adaptive problems associated
with male short-term strategies?
• Finding willing partners
• Short-term mates often have qualities
opposite those of long-term mates
• Avoiding commitment
• Avoiding expensive investment
• Avoiding or minimizing the costs mentioned
above.
• Maximizing the benefits
– Immediate fertility cues not long-term fertility
values
Evidence of adaptations for male shortterm mating strategies
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Men have lower mate quality standards
Sperm wars
All the old stuff, testis size, Kamikaze sperm etc.
Sperm count and separation
Some thoughts: Chimp past, are men’s testes getting
smaller, how might birth control effect sperm
competition
Men have greater sex drives
The Coolidge effect is evidence of section on men for
short-term mating strategies. Men on average desire 4
times the number of lifetime sexual partners
More willing to have a causal sexual encounter with a
stranger
Men are self-deceptive about choosiness.
Men have more extramarital affairs (crosscultural/universal)
More willing to pay for sex (cross-cultural/universal)
Sex Differences in Sexual Fantasies
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Uncommitted sex
Variety
Quantity
On demand
Lust not love of emotional attachment
“The most striking feature of (male fantasy) is that
sex is sheer lust and physical gratification, devoid of
encumbering relationships, emotional elaboration,
complicated plot lines, flirtation, courtship, and
extended foreplay” (Ellis & Symons)
• In contrast, women tend to fantasize about familiar
partners typically someone they are already involved
with, and with high emotional/romantic content.
Although they have less reproductive
incentive, women also derive benefits from
short-term matings. If they did not, men
would not have evolved adaptations for
sexual variety
Evidence for female cognitive adaptations for
short-term matings
• Orgasm: up-suck hypotheses
• Extramarital affairs (near universal)
• Paternal confusion
– More resources and protection
– Chimps yes, but people?
• Sleeping one’s way to the top
– Exchange for goods and services
– Sleeping with the boss for a promotion
• Social climbing
– Groupies
• Mate Switching Hypotheses
• Mate Skill Acquisition Hypotheses
– Maybe: women can hone skills of seduction without “going
all the way”
• Mate Manipulation Hypotheses
– Revenge
– A woman can manipulate by flirting with other men and not
incur the cost of getting caught in an extramarital affair.
Short-term mating costs to women
• Reputation
• As with men but more so
• Lower chances of securing a high-quality long-term
mate
• Higher childhood mortality
• If in long-term relationship (married): lower paternal
certainty can lead too less paternal investment.
• paternal confusion may lead to lower overall support
• Violence
– Angry husband (book omits this)
– Unattached women more likely to be abused by men
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Number one reason women give for having
an affair is sexual gratification
• Variables that increase likelihood of shortterm matings (contexts that lead to lower
costs and higher benefits):
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Age
Life history
Sex ratios (density dependent strategies)
Mate value
In short: cutting the best deal
• Men with more choice peruse sexual variety (less
choosy).
• Women with more choice seek long-term commitment
from high-quality men (more choosy).
Conflicts between women and men over sex
are inevitable because men and women are
pursuing different, often conflicting, sexual
strategies (Strategic Interference Theory)
• Conflicts arise over:
– Sexual Access
– The timing and frequency of sex (sexual control)
• On average men are more sexually aggressive
– Sexual withholding
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Women more than men
An aspect of choosiness
Scarcity increases value
Increase value means men are more willing to invest and
invest more (commitment: “don’t buy the cow if you
already get the milk free”
•Different perceptions about the sexual intent of the other:
• Deception about commitment
• Sexual harassment in the work place is
common because:
– Status differences in the evolutionary past
often led to sexual control differences
– Corporate/Workplace hierarchies (CEOs,
Pres., VPs, on down to low level personal)
are perceived as dominance hierarchies by
our evolved cognitive mechanism (MissMatch Theory)
• Men are more likely to pursue materetention tactics including violence
• Mate Deprivation Hypothesis
– Men who are less able to compete for the resources and
status necessary to attract women turn to sexual
aggression so not to be excluded entirely from
reproduction.
– Hypothesis was falsified!
•Correlated with men’s perception of future earning potential
Sexual Jealousy
• Men and women experience sexual jealousy
in about the same magnitude and frequency
• Different triggers
– Sexual infidelity (60% of Men, 17% of women)
– Emotional involvement (cues of long-term
diversion of investment) (83% of women, 40% of
men) “but honey it was just sex she doesn’t mean
anything to me”
• Cross-cultural
Variables affecting mate-retention tactics:
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Likelihood of infidelity
Women’s reproductive value
Age
Physical attractiveness
Men’s income and Status
Higher income
Effort towards status striving
Mate value differentials
She gets older he becomes distinguished
Jealous of younger women
He looses job or doesn’t realize potential
Jealous of higher status men
• Men more willing to resort to violent tactics
– Violence must have worked in the EEA
• Mate preferences and intra sexual competition
– Each sex, through mate choice, defines the nature and
goals of competition for the other sex.
– Men value physical appearance in women so women
compete with each other with in the domain of physical
appearance
– Women value status and resources in men so men compete
with each other for status and resources
– Conflict between the sexes is then linked to same sex
conflict
• Blame the victim?
• Media
Parental motivation:
• Psychological literature is lacking.
• Evolutionary Theory predicts self-sacrifice for sake
of offspring.
• Evolutionary Theory leads us to ask questions and
examine assumptions that other theoretical
frameworks either ignore or take for granted.
• The ultimate reason that parents love their children,
will expend lots of energy on behalf of their children,
and take great risks to protect them, is because in
the evolutionary past those individuals that did these
things and did them well had more children survive
to have children of their own than did those
individuals that did not do these things or who did
not do them as well.
Mothers are primary caretakers because:
• When a mother calculates the costs and
benefits of how much to invest, or whether or
not to invest, in a particular offspring she is
weighing the reproductive value of this
offspring against the reproduction value of
existing offspring or future offspring.
• Most insects and fish strategies is to not
invest in offspring beyond laying and
fertilizing eggs and perhaps a onetime
investment to start them off, and instead put
their energy into having lots of offspring
each with low chances of survival.
When a father is making the same
calculation he must also factor in:
• the possibility that this offspring my not be his
(PATERNAL UNCERTAINTY HYPOTHESIS)
• whether or not his investment is critical to this
child’s survival and future success
(ABANDONABILITY HYPOTHESIS)
• and the reproductive potential of investing (or
continuing to invest) in the children he has with this
mate vs. his opportunity to invest in offspring with
an other mate with greater reproductive potential
(MATING OPPORTUNITY COST HYPOTHESIS)
Paternal uncertainty theory
• Females know (with the exception victims of
cuckoos and other parasitic breeders)
• Male Seahorses know
• If there is a chance that the child is not his,
he will factor in the paternal uncertainty
percentage as an additional cost
• Matrilineal societies
Abandonability theory
• The odds that the child will survive with only
one provider.
• And knowing that since the female will have
more invested, and that one child represents
a larger proportion of total reproductive
potential for a female, she is less likely to
abandon the child and is therefore “forced”
to care for the child rather than let him/her
die.
Mating Opportunity Cost Hypothesis
• Males calculate the odds of survival for
each offspring vs. benefits of investing
in short-term mating or long-term mating
with another female with a higher
reproductive value (7 year itch?)
What are the cost and benefits associated with
parental care decisions?
• Parental care mechanisms, like other psychological
mechanisms, are innate strategies for making
decision and motivating behaviors that weigh the
ultimate reproductive costs and benefits of
alternative behaviors (proximate mechanisms).
• This leads us to ask what are the relative variables
and/or contexts that are likely to be important or
salient inputs for parental care decisions?
– 1. Genetic relatedness of offspring (KIN SELECTION)
– 2. Ability of the offspring to convert parental care into
fitness (RETURN FOR UNIT OF INVESTMENT)
– 3. Alternative uses of the resources (WEIGHING
DIFFERENT RETURNS FOR DIFFERENT INVESTMENTS)