Sex Differences In Parental Investment Flashcards
What do we mean by parental investment?
‘Any investment by the parent in an individual that increases the offspring’s chance of surviving (and hence reproductive success) at the cost of the parent’s ability to invest in other offspring’
Name 3 examples of parental investment
1) Resources
2) Time spent teaching the offspring
3) Risks taken to protect the offspring
Outline maternal investment (3 main points)
1) The female egg is very costly to produce as have to nourish offspring for 9 months so limited to the number of offspring and breastfeeding inhibits fertility
2) Essentially they make the greater prenatal and postnatal contribution
3) Also, can always be certain that she is the mother due to internal fertilisation, whereas a man cannot
How long can breastfeeding last for?
In the UK, 3-12 months but it can be up to 4 years in other countries
Why can a mother be certain she is the mother but a man cannot be certain he is the father?
Internal fertilisation
Outline paternal investment
Males either mate with as many females as possible or only guard one female to maximise reproductive success - can potentially father an unlimited number of offspring
What did Trivers argue about paternal investment?
There is an optimum number of offspring for each parent - a low-investing male could afford many offspring and favour a quantity rather than quality approach and females prefer quality and so are more choosy
What is the highest number of offspring conceived by a female?
69
What is the highest number of offspring conceived by a male?
867
What do both men and women look for in the short-term?
Men look for fertility and women look for ‘mate insurance’
What do both men and women look for in the long-term?
Men look for parenting skills and faithfulness and women look for resources, commitment and protection
Name 2 positive evaluative points for sex differences in paternal investment
1) Daly & Wilson (80)
2) Geher (07)
Outline Daly & Wilson (80)
Children under the age of 2 are at least 60 times more likely to be killed by a step-parent (almost always a stepfather) than by a natural parent which is what evolutionary theory would predict as genetically unrelated
What does Geher (07) show?
Evidence suggesting males tend to be less prepared than females
Outline Geher (07)
Studied 91 undergraduates who completed a paternal investment perception scale and were exposed to various parenting related scenarios - found no sex differences in self-report responses to parenting on the scale but there were clear differences in the ANS arousal to different parenting scenarios as males showed significantly increased heart rates when presented with scenarios that emphasised the costs of parenting - so, males biologically less prepared than females to confront issues associated with parenting
Name 4 negative evaluative points about sex differences in paternal investment
1) Most stepfathers do not kill/abuse their stepchildren & minority of biological fathers do
2) Anderson (99)
3) Sex differences in jealousy - Buss (92)
4) Difficult for the theory to explain neonaticide
What is neonaticide?
The killing of a new-born baby
Outline Anderson (99)
Measured the resources invested by father and stepfather and found that men appeared to not discriminate between children born to their current partner from a previous relationship and their own children from a previous relationship
Explain sex differences in jealousy for sex differences in paternal investment
Buss (92) - ppts imagined their partners either having sex or being in love with someone else and measured their stress responses and found men were more stressed when their partner was sexually unfaithful and women were more stressed when their partners were emotionally unfaithful
Explain why it is difficult for the theory to explain neonaticide for sex differences in paternal investment
Doesn’t make sense for a woman to kill her new-born baby - Pinker (97) said when such an act takes place, it is usually in conditions of poverty and could be regarded as an adaptationist response
Name 3 IDA points for sex differences in paternal investment
1) Culturally biased
2) Insights from non-human species
3) Reductionist
Explain why theories for sex differences in paternal investment are culturally biased
They don’t look at paternal investment in collectivist cultures which may be very different so not necessarily a universal theory
Explain insights from non-human species for sex differences in paternal investment
We can better understand the origins of human paternal behaviour by making a comparative analysis of parental investment in closely related species - the 2 most closely related are chimps and bonobos and in both males show little or no parental investment which suggests the emergence of male parenting in humans either represents a dramatic evolutionary change over our primate ancestors or the contribution of cultural learning
Explain how theories about sex differences in paternal investment are reductionist
Rowe (02) suggests an explanation of paternal investment based on just evolutionary factors is severely limited - men’s parental behaviour depends on various personal and social conditions, including the quality of the relationship with the mother, the characteristics of the child and the personality characteristics of the father
