invest more than males as they produce
fewer gametes & are certain they are the true
parent & can only have a limited number of
offspring whereas males can have unlimited.
CONSEQUENCE OF GREATER INVESTMENT
BY WOMEN: expense of childrearing means
females want to make sure their offspring are of
high quality. to do this, they may marry a man
who is caring & has resources but shop around
for good genes through extramarital affairs. The
results of a survey found that around 14% of
the population were products of affairs,
supporting this
cuckold their partners
to offset greater
investment. benefits
include additional
social support from
another male & maybe
higher quality genes.
Risks could be the
possibility of
abandonment or
violence towards her
or the other male by
the current partner
brain size increased in
response to adaptive pressures
in ancestors, so more difficult
childbirth. Now, occurs earlier in
development so infants are born
relatively immature. Also have
to breastfeed. More burdened
byt extended period of childcare
from prolonged immaturity.
greater prenatal contribution
(pregnancy) & larger
postnatal contribution too
minimum investment for females = 9 month
pregnancy & years of feeding & carrying compared
to males whose minimum is few moments of
copulation & some semen. Random mating would
me far more costly to females than males.
females would prefer quality over quantity as they
are the limiting factor in human reproduction.
consequently have to be choosier about whom they
mate with, although criteria for good mates can vary.
PATERNAL INVESTMENT
males can simply walk away
having achieved the task of
fertilisation. indiscriminate
mating can cost the woman
great amounts of time &
resources but is less costly
for males. They are not
certain of paternity so have
the choice of either mating
with lots of women in the
hope that some will mother
his children or just one
woman and keep an eye on
her to make sure it is
definitely his child.
do not want to waste
time & resources
raising another man's
genetic reproductive
potential.
the theory would predict that
paternal certainty would make the
males invest more in the offspring
if they were sure it was
biologically theirs. Contrary to
this, research assessing paternal
investment by fathers &
stepfathers has shown that men
don't discriminate between their
step children and their own
biological children from a previous
relationship.
there is also evidence of sex differences in jealousy. Men were found to be more
concerned about sexual infidelity and women more about emotional infidelity.
Physiological responses from patients when asked to picture scenes of sexual
infidelity support this as they found that men showed much more distress for sexual
than emotional infidelity. However, opposing research found that men respond with
greater arousal to ANY sexual imagery, challenging the view that sex differences in
jealousy are an adaptive response in males and females.
maybe they invest in step-children to
show their ability as resource providers
to be seen as more attractive
most males DO invest in
order to increase the
chances of reproductive
success by decreasing
infant and child mortality.
This is done by providing
resources e.g. stable food
supply to allow the famility to
live in a healthier
environment.
IDA: insights from non-human species such as
chimpanzees who are closely related to us
shows that the emergence of male parenting in
humans represents either a dramatic
evolutionary change over our primate ancestors
or the contribution of cultural learning as they
show little or no paternal investment at all.
IDA: theory is reductionist as it is very limited.
men's parental behaviour is also influenced
by personal & social conditions such as their
personality, the child's characteristics and the
quality of the relationship with the mother.
Belsky claims that childhood experiences of
parental divorce also correlate with the
degree to which men invest in the upbringing
& care of their own children.
to be successful you must pass on your genes, by preferably having 2
or more children who will do the same. while men can be promiscuous
and impregnate many other women during the time of pregnancy, women
cannot be impregnated again once already pregnant.
research if inconclusive: children under 2 are 60x more likely to be
killed by a step-parent than by a biological parent. This is what the
theory predicts as step-parents are not genetically related to the child.
However, most don't kill or abuse while some biological parents do.
evolutionary theory has
difficulties in explaining
maternal neonaticide.
according to Pinker, when this
takes place in conditions of
poverty, it could be an
adaptationist response.
psychological module that
normally induces
protectiveness is switched off
by the challenge of an
impoverished environment.
this mean both killing and
protecting are explained by
evolutionary selection.