Parental and maternal investment. Flashcards
Introduction?
This is the heart to Triver’s theory and it looks at how males and females do not invest equally.
This is said to be because the females investment is higher than a males because the females produce far less eggs (gametes) then the males do sperm.
As a result of this biological inequity, females are more choosier when picking a mate.
Maternal investment? - immaturity, enlargement, etc.
Due to the enlargement of the skull, child birth is harder on the female which makes the female investment greater.
The offspring are also branded as ‘immature’ when compared to mammals, and this is because the females breastfeed their young which causes the females to be burdened with childcare as it leads to prolonged ‘immaturity.’
Therefore, females make a greater investment both pro-natal and pre-natal.
For females the price of childcare is very high but for our ancestors the minimum childcare would have been to feed and carry the baby - it has evolved.
We are biologically obliged to invest into our offspring.
Evaluation - Baker and Bellis.
Childbearing means that women want good quality mates, and one way to ensure this is to marry high quality men who are willing to invest their resources.
Baker and Bellis supported this with a magazine study involving 2700 women.
It was found that 14% of the population have came from affairs, this shows that females look for good quality offspring’s in other mates but stay married with their original partners for the resources.
Evaluation - Michalski and Shacefold.
They showed that maternal grandmothers invest more attentive care to their grandchildren when compared to the grandfathers.
Similar results were also shown with aunties and uncles.
This shows the idea that men and females invest different amounts into their children and women invest more in the parental line than males.
Parental investment? Cuckoldry, sexual jealousy, etc.
Sex differences show that males can opt out of parental investment whereas females cannot.
The theory suggests that sex leads to a larger investment is sexually discriminating.
When males do invest their resources they are pressured to protect themselves from cuckoldry.
This is because males do not want to invest their resources into an offspring for it to not be theirs, it is a waste of resources and they don’t want it to misdirected…
When a male is with their female partner and they are unfaithful they are at risk in investing into an offspring which is not theirs.
With women, males who are unfaithful means that women are at risk at losing the person who invests into their offspring.
Sexual jealousy has evolved from this and it has been found that males are more jealous of the sexual act (cuckoldry) and females are more jealous of the emotional shift (investments.)
Evaluation - males do invest, Reid, Anderson.
It has been found that males do invest as it has been shown that joint parental care has larger benefits (e.g. successful reproduction.)
With males, investing in an offspring costs to do so and it has been found that males may actually restrict their reproductive opportunities to invest in their one offspring as this ensures their survival.
Reid found that males invest and it helps the family and their survival because they are able to live in a healthier environment, etc.
Anderson measured the resources invested in fathers and step fathers.
He found that males do not discriminate against children that are not theirs and invest in the offspring still.
This shows, overall, that parental certainty is not an issue.
Evaluation - Rowe, evolutionary, limited, Belsky + divorce.
Rowe said that the parental investment theory overall is biased as it only comes from an evolutionary P.O.V which makes the theory reductionist.
Men’s behaviour can be down to other factors such as social factors or their childhood.
You need to look at the quality of relationships and other contributing factors.
Belsky et al pointed out that divorce intends to correlate with the degree to which men invest in their offspring.
This supports the idea that the parental investment theory is reductionist.
