WSTA01H3 Chapter Notes - Chapter 1: Parental Investment, Ovulation, False Dilemma

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Published on 20 Apr 2013
Chapter 1: Psychological Sex Differences through Sexual Selection
both sexes have sweat glands because both sexes have faced the adaptive problem of thermal regulation
both sexes have similar (although not identical) taste preferences for fat, sugar, salt, and particular amino acids because both sexes have faced similar (although
not identical) food consumption problems
both sexes grow calluses when they experience repeated rubbing on their skin because both sexes have faced the adaptive problem of physical damage from
environmental fiction
in the physical realm, women have faced the problem of childbirth; men have not
women, therefore, have evolved particular adaptations that are absent in men, such as a cervix that dilates to 10 centimetres just prior to giving birth, mechanisms
for producing labour contractions, and the release of oxytocin in the bloodstream during childbirth
because fertilization occurs internally within the woman, men have faced the adaptive problem of uncertain paternity in putative offspring
men who failed to solve this problem risked investing resources in children who were not their own
all people descend from a long line of ancestral men whose adaptations (i.e., psychological mechanisms) led them to behave in ways that increased their
likelihood of paternity and decreased the odds of investing in children who were putatively theirs but whose genetic fathers were other men
this does not imply, of course, that men were or are consciously aware of the adaptive problem of compromised paternity
women faced the problem of securing a reliable or replenishable supply of resources to carry through pregnancy and lactation, especially when food resources
were scarce (e.g., during droughts or harsh winters)
all people are descendants of a long and unbroken line of women who successfully solved this adaptive challenge – for example, by preferring mates who showed
the ability to accrue resources and the willingness to provide them for particular women
those women who failed to solve this problem failed to survive, imperiled the survival chances of their children, and hence failed to continue their lineage
Sexual Selection Defines the Primary Domains in Which the Sexes Have Faced Different Adaptive Challenges
Darwin sculpted what he believed to be a second theory of evolution – the theory of sexual selection
sexual selection is the causal process of the evolution of characteristics on the basis of reproductive advantage, as opposed to survival advantage
sexual selection comes in two forms
first, members of one sex can successfully out-compete members of their own sex in a process of intrasexual competition
whatever characteristics lead to success in these same-sex competitions – be they greater size, strength, cunning, or social skills – can evolve or increase in
frequency by virtue of the reproductive advantage accrued by the winners through increased access to more numerous or more desirable mates
second, members of one sex can evolve preferences for desirable qualities in potential mates through the process of intersexual selection
if members of one sex exhibit some consensus about which qualities are desirable in the other sex, then members of the other sex who possess the desirable
qualities will gain a preferential mating advantage
Hypotheses about Psychological Sex Differences Follow from Sexual Asymmetries in Mate Selection and Intrasexual Competition
Paternity Uncertainty
because fertilization occurs internally within women, men are always less than 100 per cent certain that their putative children are genetically their own
women are always 100 percent certain that the children they bear are their own
Identifying Reproductively Valuable Women
because women's ovulation is concealed and there is no evidence that men can detect when women ovulate, ancestral men had the difficult adaptive challenge of
identifying which women were more fertile
although ancestral women would also have faced the problem of identifying fertile men, the problem is considerably less severe both because most men remain
fertile throughout their life span, whereas fertility is steeply age graded among women, and because women invest more heavily in offspring, making them the
more 'valuable' sex and more intensely competed for by men seeking sexual access
Gaining Sexual Access to Women
because of the large asymmetry between men and women in their minimum obligatory parental investment – nine months gestation for women versus an act of
sex for men – the direct reproductive benefits of gaining sexual access to a variety of mates would have been much higher for men than for women throughout
human evolutionary history
therefore, in social contexts that allowed some short-term mating or polygynous mating, men who succeeded in gaining sexual access to a variety of women –
other things being equal – would have experienced greater reproductive success than men who failed to gain such access
Identifying Men Who Are Able to Invest
because of the tremendous burdens of a nine-month pregnancy and subsequent lactation, women who selected men who were able to invest resources in them
and their offspring would have been at a tremendous advantage in survival and reproductive currencies compared to women who were indifferent to the
investment capabilities of the men with whom they chose to mate
Identifying Men Who Are Willing to Invest
copulating with a man who had resources but who displayed a hasty post-copulatory departure would have been detrimental to the woman, particularly if she
became pregnant and faced raising a child without the aid and protection of an investing father
a man with excellent resource-accruing capacities might channel resources to another women or pursue short-term sexual opportunities with a variety of women
a woman who had the ability to detect a man's willingness to invest in her and her children would have an adaptive advantage compared to women who were
oblivious to a man's willingness or unwillingness to invest
- these are just a few of the adaptive problems that women and men have confronted differently or to differing degrees
- other examples of sex-linked adaptive problems include those of coalitional warfare, coalitional defense, hunting, gathering, combating sex-linked forms of
reputational damage, embodying sex-linked prestige criteria, and attracting mates by fulfilling the differing desires of the other sex – domains that all have
consequences for mating but are sufficiently wide-ranging to span a great deal of social psychology
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