PARENTAL INVESTMENT (PI) PSYCHOLOGY A2 RELATIONSHIPS

PARENTAL INVESTMENT (PI)

SEX DIFFERENCES
Human males can opt out of parental investment in a way females can not. By using reproductive effort on courtship and mating. Males can devote little in comparison to parental care (Daly and Wilson, 1978).
WHY DO HUMAN FEMALES INVEST MORE?- As brain size increased by adaptive pressures from our ancestors, resulted in more
difficult childbirth due to enlargement of the skull
- To compensate childbirth it happens earlier in development- infants are born
premature compared to other animals
- Human females of breastfeed and are burdened by extended period of childcare that
results in prolonged immaturity
- Human mothers make greater parental contribution of recourses through pregnancy
and postnatal contribution as well.
THE COSTS OF MATERNAL INVESTMENT - Human females high- minimum investment nine month pregnancy followed by years
of feeding and carrying.
- Minimum of a guy- few moments of copulation and teaspoonful of seamen (Symons,
1979)
- Random mating for females is more costly.
PATERNAL INVESTMENT AND CUCKOLDRY- Men are under pressure to protect themselves from cuckoldry (investing in kids that
are not their own) if they do invest parentally
- As men make considerable investment to their kids they have greater concern than
females about the fidelity of the males (Miller, 1998)
- Try to make sure their care is not misdirected towards non- relatives through adultery
laws that define the offence in terms of woman’s marital status rather than the mans.
SEXUAL AND EMOTIONAL JEALOUSY A man whose mate was unfaithful risks investing in kids that are not his.
Woman risks diversion of recourses away from the family.
Sexual jealousy may have been evolved as a solution to these problems (Buss, 1995). Men are more jealous of the sexual act and women are jealous of the shift in emotional focus and loss of recourses.
　
　
　
　
　
　
　
　
　

COMMENTARY

MATERNAL INVESTMENT Infant dependency means females want male providers.
Expense of childbearing means females want to ensure good quality offspring so they do not waste their efforts.
- They marry a man who has good recourses and caring but look for good genes through extra marital affairs with good looking guys with no recourses
- UK magazine 2700 UK women have mistaken paternity
- Baker and Bellis (1990)- 14% of population are products of extra marital affairs from results of a survey.
EVIDENCE FOR SEX DIFFERENCES IN JEALOUSYBuss et al (1992)- Male US students more concerned about sexual infidelity
For females it was emotional infidelity
Supported by psychological responses were respondents were asked to imagine scenes of sexual or emotional infidelity- men showed more response for sexual than emotional.
SEX DIFFERENCES IN PARENTAL INVESTMENT 2008- Conservative MP Micheal Grove
‘Lad mags’ such as Zoo and Nuts reinforced a ‘shallow approach’ to women linked to a rise in reckless fatherhood and family breakdown.
Geher et al (2007):
91 non parent hetro-sexual undergraduates completed a parental investment perception scale.
Included statements such as ‘I am very prepares to raise a child at this time in my life’ additionally exposed to various parenting related scenarios.
No sex differences in self-report responses to parents on parental investment perception scale, clear differences in ANS arousal increased heart rate when presented with scenarios that emphasises the costs of parenting (e.g. unable to work).
Researchers concluded that, consistent with predictions from PI theory males are biologically less prepared than females to confront issues associated with parenting.
AN EVOLOUTIONARY PERSPECTIVEPI theory- parents maximise their reproductive fitness by gradually withdrawing their investment from older kids in favour of younger siblings. First and last born hold a privileged status in parental investment.
- 1^st born closest to reproducing genes to the next generation
- Last born need more parental investment
Parents are more pressured in doing more investment in them than the middle born kids.
Andrew (1996)- 1600 US adolescents survey
Severe suicide attempts are more significant in middle kids than first or last born. Middle kids would need to make risk attempts to expect more parental investment. Survey supports view that suicidal behaviour may well be an adaptive response in line with predictions of the PI theory.