Parent offspring conflict
- Trivers (1974) proposed that children desire greater investment than their parents are selected to provide. parents allocate resources to all offspring to ensure that the maximum nuber of survives... therfore conflict occurs, as indivdiual children want more resources from parents than they are prepared to give.
- PI includes actions performed by parents to increase offsprings chance of survival while reducing parents ability to invest in other offspring either existing or future ones
- investing in new offspring rather than in heavily increasing self sufficient children enhances parents reproductive success
- each child regards themselves as more important that the other sibling/s
- competition between siblings for resources is inevitable = sibling rivalry
- parent offspring rivalry begins before birth for example mothers having high blood pressure due to feotus needing nourishment from her
- children use various strategies to manipulate their parents into allocating them resources like crying or smiling
- older parents will tolerate the demands of young infancts more as they are not compramising their future reoriductive potential becuase they are not having any more children which means it makes sense to centre resources on exising ones
Parent offspring conflict
According to Buss (1999)
- Children wish to delay weaning as long as possible, often in contrast to mothers wishes.
- parents encourage children to value and assist siblings more than they naturally would as this enhances parents reproductive success.
- therfore parents punish conflict between siblings and reward cooperation.
Simpson (1999) makes the following predictions based on Trivers's theory:
- conflict should be increased when half siblings exist because they are only 25% genetically similar
- therfore 4 half siblings must survive and reproduce if the genes of an infant are to be fully replicated
- where there are step parents and 2 or more half siblings plus full siblings offspring should demand aprox 4 times as much investment as their parents are willing to give = long and intense periods of parent-offspring conflict
- conflict should be greater in families with young mothers
- they have many child bearing years ahead of them and more reproductive opportunities than older mothers approaching menopause.
- younger mothers are less tolerant of the demands of high cost infants
Research - Parent offspring conflict
Daly and Wilson (1985), (1988)
FOUND - that even when financial resources and marital staus are held constant, younger mothers are more likely to kill infants than older mothers, and older mothers are less likely to abuse or harm infants SUPPORTS simpsons theory Rimm (2002) FOUND - sibling rivalry most intense when children are close in age and need more resource investment. Sibling rivalry was also intense when one sibling was gifted. Trivers (1985) FOUND - that herring guls manipulate parents by appearing smaller than they are to elicit feeding.
Evaluation - Parent offspring conflict
- children have motivations to feel negatively towards siblings, as they are co-competitors for limited parental resources but are also motivated to have positive regard for siblings as they share 50% genetic similarity - explains they contradictory behaviour that siblings display
- human parents demonstrate a strategy to cope with sibling rivalry by taking them along to different devlopment paths, maximising each indivdiuals strengths reducing conflict and producing different indivdiuals
- Evolutionary explanations of PI are based on the idea that human behaviour is adapted to cope with life in the Pleistoncene era and this therefore may not be representative of modern day
- Reductionist ignores any other explanations other than adaptive fitness
- Deterministic sees parental behaviour as driven by biological factors with no input of free will