> DALY AND WILSON say that by expending a large part of their reproductive effort on courtship & mating, males of most species can afford to devote rather little, in comparison to females, to parental care.
> Parental investment theory suggests that the sex that makes the larger investment will be the more sexually discriminating.
> Parental investment theory suggests that the sex that makes the smaller investment will compete for access to the higher-investing sex.
> The investment made by human females is considerably greater than that made by males (e.g. the female produces far fewer eggs in her lifetime than the male produces sperm).
> Females can be certain that they are the mother as they carry their child, whereas men can't always be sure they're the father.
Why do human females invest more? -
> Brain size increased in response to adaptive pressures among distant ancestors which resulted in more difficult child birth due to an enlargement of the skull, to compensate for this babies are born immature compared to other animals.
> Human females breastfeed their young & so are more burdened by this extended period of childcare. Mothers thus make greater prenatal contribution (pregnancy) & a larger postnatal contribution as well.
The costs of maternal investment -
> SYMONS said for female ancestors the minimum investment would've been a 9 month pregnancy followed by years of feeding & carrying. For men, however, it would've been a few moments of copulation & some semen.
> GOETZ AND SHACKELFORD said that indiscriminate mating could cost a woman a great deal in terms of time & resources, whereas indiscriminate mating tends to be much less costly for a man.
Paternal investment and cuckoldry -
> When males invest parentally (resources) they are under pressure to protect themselves from the possibility of cuckoldry (investing in kids that aren't theirs).
> MILLER said because human males make a considerable investment in their children, they have greater concern than females about the fidelity of their mates.
Sexual and emotional jealousy -
> A man whose mate was unfaithful risked wasting resources on offspring that…