PARENTAL INVESTMENT

MATERNAL INVESTMENT
1. invest more than males as they produce fewer gametes & are certain they are the true parent & can only have a limited number of offspring whereas males can have unlimited.
  1. CONSEQUENCE OF GREATER INVESTMENT BY WOMEN: expense of childrearing means females want to make sure their offspring are of high quality. to do this, they may marry a man who is caring & has resources but shop around for good genes through extramarital affairs. The results of a survey found that around 14% of the population were products of affairs, supporting this
    1. cuckold their partners to offset greater investment. benefits include additional social support from another male & maybe higher quality genes. Risks could be the possibility of abandonment or violence towards her or the other male by the current partner
2. brain size increased in response to adaptive pressures in ancestors, so more difficult childbirth. Now, occurs earlier in development so infants are born relatively immature. Also have to breastfeed. More burdened byt extended period of childcare from prolonged immaturity.
  1. greater prenatal contribution (pregnancy) & larger postnatal contribution too
3. minimum investment for females = 9 month pregnancy & years of feeding & carrying compared to males whose minimum is few moments of copulation & some semen. Random mating would me far more costly to females than males.
  1. females would prefer quality over quantity as they are the limiting factor in human reproduction. consequently have to be choosier about whom they mate with, although criteria for good mates can vary.
PATERNAL INVESTMENT
1. males can simply walk away having achieved the task of fertilisation. indiscriminate mating can cost the woman great amounts of time & resources but is less costly for males. They are not certain of paternity so have the choice of either mating with lots of women in the hope that some will mother his children or just one woman and keep an eye on her to make sure it is definitely his child.
  1. do not want to waste time & resources raising another man's genetic reproductive potential.
    1. the theory would predict that paternal certainty would make the males invest more in the offspring if they were sure it was biologically theirs. Contrary to this, research assessing paternal investment by fathers & stepfathers has shown that men don't discriminate between their step children and their own biological children from a previous relationship.
      1. there is also evidence of sex differences in jealousy. Men were found to be more concerned about sexual infidelity and women more about emotional infidelity. Physiological responses from patients when asked to picture scenes of sexual infidelity support this as they found that men showed much more distress for sexual than emotional infidelity. However, opposing research found that men respond with greater arousal to ANY sexual imagery, challenging the view that sex differences in jealousy are an adaptive response in males and females.
      2. maybe they invest in step-children to show their ability as resource providers to be seen as more attractive
2. most males DO invest in order to increase the chances of reproductive success by decreasing infant and child mortality. This is done by providing resources e.g. stable food supply to allow the famility to live in a healthier environment.
3. IDA: insights from non-human species such as chimpanzees who are closely related to us shows that the emergence of male parenting in humans represents either a dramatic evolutionary change over our primate ancestors or the contribution of cultural learning as they show little or no paternal investment at all.
  1. IDA: theory is reductionist as it is very limited. men's parental behaviour is also influenced by personal & social conditions such as their personality, the child's characteristics and the quality of the relationship with the mother. Belsky claims that childhood experiences of parental divorce also correlate with the degree to which men invest in the upbringing & care of their own children.
to be successful you must pass on your genes, by preferably having 2 or more children who will do the same. while men can be promiscuous and impregnate many other women during the time of pregnancy, women cannot be impregnated again once already pregnant.
research if inconclusive: children under 2 are 60x more likely to be killed by a step-parent than by a biological parent. This is what the theory predicts as step-parents are not genetically related to the child. However, most don't kill or abuse while some biological parents do.
1. evolutionary theory has difficulties in explaining maternal neonaticide. according to Pinker, when this takes place in conditions of poverty, it could be an adaptationist response. psychological module that normally induces protectiveness is switched off by the challenge of an impoverished environment. this mean both killing and protecting are explained by evolutionary selection.

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PARENTAL INVESTMENT

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	Created by diana.m1629 about 10 years ago