Flashcards in Parental Investment Deck (15)
What is the overview of maternal investment?
The investment made by females in considerably more than males, females produce fewer gametes in their lifetime. Females are also certain that they are the true parent of the child whereas the male may not be, this is because of internal fertilisation.
Maternal investment- why do human females invest more?
Brain size increased which resulted in more difficult childbirth due to the enlargement of the skull. Because of this, childbirth occurs earlier compared to other animals. Humans also breastfeed their young and so are more burdened by this extended period of childcare. Human mothers make both the greater prenatal and postnatal contribution.
Maternal investment- the costs of maternal investment
For females ancestors, the minimum parental investment would have been 9 months of carrying, followed by years of feeding and looking after. For males, however, it was a 'teaspoon of semen and copulation.' The result is an enormous difference in the potential maximum reproductive success of the sexes, so making random mating all the more costly for human females
Paternal investment- overview
The minimum obligatory investment for males is less. A woman CSI produce only a limited number of offspring whereas a man can father an unlimited number. A male can simply walk away after fertilisation whereas a woman can't. Indiscriminate mating could cost a woman a lot in terms of resources and time. It is less costly for males.
What is the overview of parental investment?
Males of most species can devote rather little to parental care. The sex that makes the larger investment will be more sexually discriminating. In humans this is females and so they are more discriminating in their choice of partner
Paternal investment- paternal investment and cuckoldry
When males do invest, they are under pressure to protect themselves from the possibility of cuckoldry. Males have a greater concern about the fidelity of their mates. As a result, they try to ensure that their care is not misdirected towards non-relatives.
Paternal investment- sexual and emotional jealousy
A man whose mate was unfaithful risked investing in offspring that was not his own. Whereas a woman who's mate was unfaithful risked the diversion of resources. Sexual jealously has evolved as a solution to these problems. Men are more jealous of the sexual act and women of the emotional act
Evaluation- the consequences of greater investment by females
Extra marital affairs
The expense of child rearing means that females want to ensure good quality offspring so they don't waste their efforts. To achieve this many women marry a man with good resources but shop around for good genes through extra marital affairs. It is estimated that 14% of the population were products of extra marital affairs
Evaluation- the consequence of greater investment by females
The benefits and risks of cuckoldry
Some women may attempt to offset their greater parental investment by cuckolding their partner. Women can obtain be benefits such as extra social support and maybe higher quality genes, however, some risks can occur, such as abandonment and the use of mate retention strategies
Evaluation- commentary on parental investment
Males do invest
In humans, makes may restrict their reproductive opportunities and invest more in each individual offspring. Research by Reid supports the claim that males do contribute to parenting by providing resources e.g. Food supply and this allows the family to love I'm healthier environments, resulting in a decrease in infant/child mortality.
Evaluation- commentary on parental investment
Parental certainty is not always an issue for human males
Parental investment theory would predict fathers investment would be greater if they know the child is biologically theirs. However, Anderson found that stepfathers did not discriminate between their biological and step children.
Evaluation-commentary in parental investment
Evidence for sex differences in jealously
Buss found that male us students indicates more concern about sexual infidelity whereas female students showed more concern about emotional infidelity. This is supported by physiological responses when participants were asked to imagine scenes of emotional and sexual infidelity. Males showed more distress for sexual and greater arousal. This challenged the view that sex differences are adaptive
Evolutionary explanations are reductionist
Rowe suggests an explanation for paternal investment based only on evolutionary factors is limited. Paternal behaviour depends on; quality of relationship with mother, characteristics of child and personality of the father. Belsky also included; childhood parental divorce tends to correlate with the degree to which men invest.
Paternal investment: insights from non-human species
In both species closely related to humans, males show little or no parental investment. This suggests that the emergence of male parenting in humans representing either a dramatic evolutionary change or the contribution of cultural learning