parental investment Flashcards
parental investment
any investment by a parent in an offspring that increases the chance that offspring will survive at the expense of the parents ability to invest in any other offspring
males have
low parental investment
why do men have low parental investment
as they have low paternity confidence and they can produce a vast number of offspring in their lifetime so it isnt necessary to invest heavily in any one child
why does it make reproductive sense for males to reproduce with as many females as possible
it enables more of his genes to be passed on
females have
high parental investment
why do females have high parental investment
they have high maternity confidence (100% sure the child is theirs), they carry the child for 9 months and most women can only have a maximum of 12 pregnancies in their lives
- so they must invest heavily in their offspring to ensure their genes are passed on and the children survive
why does it make reproductive sense for women to be choosy
due to high parental investment, a female will only mate with a male that she can be sure will provide and protect her and her offspring
- giving her the best opportunity for her genes to survive
difference in males and females anisogamy
females - only one large egg released per month
males - millions of small sperm
difference in internal fertilisation and gestation
females - only one conception chance per month and only one foetus per year (all offspring carry her genes)
males - could desert and fertilise many other females (paternity never certain)
difference in lactation
females - feeding offspring and suppressed ovulation for several years
males - not involved
A strength of differences in parental investment comes from Clark and Hatfield (1989)
Clark and Hatfield sent attractive male and female Psychology students across the university
campus. They approached other students with the question “I have been noticing you around
campus. I find you to be very attractive. Would you go to bed with me tonight?”. 75% of the
males approached agreed to the request, whereas 0% of females agreed.
E: This is a strength because the findings suggest that females are choosier than men when
it comes to casual sex – arguably because of their higher parental investment. Whereas
the males were more laidback when it came to casual sex – arguably because it makes
reproductive sense for them to mate with as many females as possible as this will enable
more of his genes to be passed on. Evolutionary theory suggests that these behaviours
have evolved because males have low parental investment and lack paternity certainty
whereas women have both high parental investment and maternity certainty.
L: Therefore, this adds further support and validity to the theory of differing parental investment.
counter argument
However, the study itself has low population validity as it only used a
sample of university students from one university campus. It could be expected that due to
their young age and environment they would be more used to the concept of casual sex and
so students may have given a response that doesn’t reflect that of all people. The results
therefore provide only limited evidence for sex differences relating to parental investment
A limitation of research into parental investment is that it may not be as relevant to today’s
society.
Due to changes in social attitudes, it is now more acceptable for women to be sexually active
and to talk freely about sex. Sex is not always directly linked to reproduction as women are
now less dependent than previous generations so male resources are less important.
Women’s greater role in the workplace means they are no longer dependent on men.
Bereczkei (1997) suggests women no longer have resource orientated mate preferences.
Chang (2001) compared partner preferences in China over 25 years, some changed, and
others remained the same, changing in line with social changes. In addition to this, access
to contraception has clearly had an impact on sexual behaviour.
E: This is a limitation because the findings of such research might not be relevant today.
L: Therefore, the results may lack temporal validity and the social and cultural climate should
be considered when using evidence to support evolutionary theory.
