Learning Table 4: Evolutionary Explanations of human reproductive behaviour: - The r/ship between sexual selection and human reproductive behaviour.
How evolution may have shaped the sexual preferences,
behaviours and r/ships of men & women today.
The evolutionary perspective on r/ships argues that human
reproductive behaviours have their origins in the evolutionary
past and exist because they conveyed survival or reproductive
advantages to our distant ancestors.
Darwin (1974) came up with the theory of sexual selection to
explain reproductive successes. He proposed 2 processes in which
it takes place.
Intrasexual selection (mate competition): usually males

Members of one sex (usually males) compete with each
other for access to members of the other sex. The victors are
able to mate and pass on their genes whereas the losers do
not. The victors’ traits will be passed on to the next
generation. An example of this is the way in which male
stags fight over females.
Intersexual selection (mate choice): Usually females
 This form involves the preferences of one sex for members
of the opposite sex who possess certain qualities e.g. if
females preferred taller males, there would be an increase in
the numbers of tall males over time.
 Therefore, the preference of one sex determine the areas in
which the other sex must compete. This may be in terms of
Plumage (e.g. peacock) or economic resources (e.g. in
humans)
 These indicators reveal traits that could be passed onto
offspring (selection for good genes) and chances of the mate
being able to give protection & support offspring (selection
for good parents)
 Human beings are ‘pre-programmed’ to attend to these
displays and mate with the individual who possess them.
Partner Selection
(A01)
Long-term preferences
 Both sexes invest heavily in any offspring and consequently,
sexual selection favours high levels of choosiness in both
males and females.
 Poor long-term mate choices could be disastrous for both
sexes as they would waste valuable resources.
 Women have an obligatory biological investment in their
children and therefore are particular about their choice of
mate. They are attracted to males who are 1) able to invest
resources 2) able to physically protect 3) show promise as a
good parent 4) are sufficiently compatible to ensure minimal
costs to her and her children (Buss, 2003)
 Males are most attracted to females who display signals of
fertility, an indication of reproductive value, suggesting a link
between sexual selection and human reproductive
behaviour.
Research Support and Methodological Commentary
P: Furthermore, a substantial cross-cultural study conducted by Buss (1989) explored what males & females looked for in a marriage partner.
E: The study involved over 10,000 people from 37 different cultures and found:
1) Women desired mates who were ‘good financial prospects’ more than men 2) Men placed more importance on physical attractiveness
because this provides cues to a woman’s health, her fertility and reproductive value.
3) Men wanted mates younger than them – indicating men valued increased fertility in potential mates.
4) Both sexes wanted mates who were intelligent (linked to skills at parenting), kind (linked to interests in long-term relationships) and
dependable (linked to willingness to help a mate in times of trouble).
E: This supports the theory of sexual selection because the younger the woman, the greater the fertility meaning they can reproduce.
Additionally, women want good financial prospects from men in order to provide her and her offspring so they have the best chance of
survival.
L: These findings are consistent with the theory of sexual selection, providing credible support for the relationship between sexual selection
and evolutionary explanations of human reproductive behaviour overall.
MI  Commentary on Buss (1989) Methodology
P: One strength of Buss’ (1989) study is that it has high population validity.
E: This is because it was conducted on 10,000 people in a variety of countries with different religions, ethnicity, political views and economic
factors.
E: This means that the findings that men look for younger women because of fertility and women look for men who have money, status and
provide for them can be applied across cultures and generalised
L: Consequently, Buss’ study has high external validity, which in turn increases the support it gives for the relationship between sexual
selection, and in turn, making the link between the two more credible.
(A02 - Research support for long term preferences)
The importance of fertility
P: There is evidence to support the importance of fertility as
indicator of reproductive behaviour.
E: For example, Miller (2007) calculated the tips earned by
lap dancers at varying stages of their menstrual cycle and
found that those girls who were in the fertile oestrus phase
of their cycle (sexually receptive) earned almost as twice the
value of tips compared to girls who were not in oestrus.
E: This supports the theory because at this stage in the cycle,
females are more likely to become pregnant and reproduce.
L: Suggesting a link between sexual selection and human
reproductive behaviour.
(A02 – Contradictory evidence for Long term preferences)
P: A study that contradicts evolutionary explanations and therefore the link
between sexual selection and human reproductive behaviour is provided by
Strassberg (1999).
E: He found that more men answered internet ads from women advertising
financial success and ambition than those advertising attractiveness or a
passionate nature.
E: This contradicts the evolutionary explanation because men were not
seeking younger, more fertile women which ‘attractiveness or a passionate
nature’ would imply.
E: In addition, Kenrick (1996) also rejected the hypothesis that men wanted
younger females.
E: They found that teenage males are most attracted to women who are 5
years older than them.
E: This also contradicts the theory that men are attracted to younger women
because of increased fertility.
L: Which in turn, reduce the credibility of the evolutionary explanation in
explaining the link between sexual selection and human reproductive
behaviour.
Commentary on Kenrick (1996) Methodology
P: Nevertheless, one issue with Kenrick (1996) is that it lacks population
validity.
E: This is because it was conducted on teenage males.
E: It is an issue because it could be that adolescent males are not interested in
long-term mating and impregnating women at that age and therefore are
purely looking at short-term mating preferences. They may find an older
woman ‘a challenge’ and are attracted to them to meet that challenge.
L: Therefore the validity of this study could be questioned which in turn
questions whether it can really criticise the theory that men ‘prefer’ younger
fertile women. As a result, this may in fact improve the credibility of the link
between sexual selection and human reproductive behaviour because the
evidence used to contradict it can be falsified.
Evaluation/Synopticity
Ethics
P: There are ethical implications when drawing on the findings and
conclusions of this research, as much of it is classed as ‘socially sensitive’, in
that it creates divisions between groups of people e.g. males and females.
E: Firstly, they reinforce existing gender stereotypes (Alpha Bias), in that men
are seen as the providers and women look after the babies.
E: Secondly, the theory also suggests that female subservience is natural
behaviour and that male promiscuity is acceptable as it merely reflects a
genetically determined tendency towards polygyny.
L: Psychologists must be aware of these issues when conducting such studies
and deal with them appropriately through the use of right to withdraw from
any studies, debrief them fully and offer psychological support if needed.
Reductionist
P: One issue with evolutionary explanations in looking for a relationship
between sexual selection and human reproductive behaviour is that they are
reductionist.
E: This is because they reduce human reproductive behaviour purely down
to simple genetic pressures (nature), for example, men wanting to spread
their genes in order to survive and reproduce.
E: Although this makes evolutionary explanations of human reproductive
behaviour easier to understand, they nevertheless, fail to offer a complete
explanation of human reproductive behaviour. For example, they fail to
consider the whole aspect of the individual such as the role of social
constructionism in shaping our reproductive behaviour (nurture).
L: As a result, the evolutionary approach in suggesting the link between
sexual selection and human reproductive behaviour has weak explanatory
power because they fail to offer a complete explanation on why individuals
would reproduce otherwise. A more interactionist explanation maybe more
appropriate.
Post-hoc Theory
P: One problem with evolutionary explanations in explaining the link
between sexual selection and human reproductive behaviour is that it is a
‘post-hoc’ theory. This means that it explains behaviour after it has
happened rather than making predictions about what is going to happen and
then testing it.
E: Evolutionary theories suggest that certain behaviours that we
demonstrate today make reproduction more likely and that the genes
associated with that behaviour are passed down the generations.
E: This isn’t testable as you would have to isolate a group of humans from all
other influences for many years to see if particular genes persist in the
population.
L: Therefore this issue means that it does not fulfil one of the goals of
science in Psychology and therefore the credibility of these explanations can
be questioned.
A01
Short-term preferences: The tendency to engage in casual sex
 According to parental investment theory, men evolved a greater
desire for casual sex and seek sex early in a relationship.
Whereas female behaviour would not have the same
evolutionary pressures.
 For example, over one year, a male could impregnate a large
number of women and pass on his genes, whereas a female who
had sex with the same number of men would only produce one
child.
 In contrast to women, men have lower standards in short-term
mating and show a decrease in attraction following sex which is
an evolved adaptation to prevent them spending too long with
one woman (Buss & Schmitt, 1993)
Men tend to seek and desire a greater number of sexual
partners than women (Polygamy Vs Monogamy)
 Males and females are subject to different selective pressures.
These differences occur due to anisogamy – differences
between the nature and amount of gametes (sperm & eggs)
produced.
 Males produce a lot of small, highly mobile sperm and can
fertilise many females at little cost to reproductive potential.
They cannot be sure of paternity, so natural selection favours
male behaviours maximizing the number of potential
pregnancies.
 Women however, produce few, large eggs – each one
representing a sizeable reproductive investment, although she is
always sure of maternity. She is choosier.
(A02 - Research support for short-term preferences)
P: There is empirical support to suggest that males have evolved a greater desire for casual sex than females.
E: For example, Clarke & Hatfield (1989) conducted a study on students. Men and women experimenters approached strangers on campus
and said ‘I’ve noticed you around, I find you very attractive.’ & then asked them 1 of 3 Q’s: go on a date? Come to my apartment? Have sex
with me? They found that females: 50% agreed to go on date, 6% back to apartment, 0% to have sex. Males: 50% agreed to go on date, 69%
willing to go back to apartment, 75% agreed to have sex.
E: These sex differences provide compelling evidence that men have evolved psychological mechanisms to ensure success in short-term
mating. These include as desire for sexual variety, the tendency seek sex straight away & willingness to consent to sex with strangers.
L: As a result, providing credible support for the relationship between sexual selection and human reproductive behaviour.
P: There is empirical support for the assumption that men tend to seek and desire a greater number of sexual partners than women.
E: For example, Buss & Schmitt (1993) asked how many sexual partners people would ideally like over the next 2 years, the next decade and
during their lifetime and found, on average, men would like 8 partners over the next 2 years compared to women’s 1 partner. Also, over a
lifetime, the averages were 18 (men) and between 4 and 5 (women).
E: Furthermore, Schmitt (2003) tested this idea (men lots of sexual partners, women less but choose better). He surveyed 16,288 people from
53 countries. In every country men reported wanting to have sex more than women.
L: This suggests that men have an evolved adaptation to prevent them spending too long with one woman in order to pass on their genes to
reproduce, supporting evolutionary theory and the link between sexual selection and reproductive behaviours.
 Determinism Vs Free Will (A GREAT PEEL to put in your work!!)
P: One issue with this explanation is that it is deterministic. This is because it
shows how human behaviour might be constrained by its evolutionary past –
in the fact that it is biologically determined; meaning that men have the right
to spread their genes, sleep with as many women in order to reproduce and
pass on their genes.
E: Although this explanation gives an appreciation of the role of physiology
and genes in sexual selective behaviour it nevertheless has its flaws. This is
because if sexual selection is caused externally, then an individual is not
responsible for their behaviour.
E: Thornhill & Thornhill (1983) controversially argued that men who are
unable to mate are driven to select an alternative strategy. They cite the
behaviour of the male Panorpa Scorpion Fly who inseminates unwilling
females by securing the female’s wings in an abdominal clamp, showing that
rape occurs ‘naturally’ and therefore suggesting that it is an adaptive
strategy. As suggested, if behaviour is externally caused, then the individual
is not responsible for their behaviour. However, most people feel morally
responsible for their actions and hold others responsible for their actions –
and most men do not commit rape. They have ‘free will’ and a choice on
whether they commit these acts or not. Biological determinism is sometimes
put forward as an argument for the absence of moral responsibility.
L: Evolutionary explanations for the relationship between sexual selection
and human reproductive behaviour can therefore be argued to be
controversial and lack explanatory power.
Exam Questions and advice.
1a. Outline research into the relationship between sexual selection and human reproductive behaviour (8 marks) A01 POINTS ONLY!
1b. Evaluate the research that you have outlined in 1a (16 marks) A02 POINTS ONLY!!!
2. Discuss the relationship between sexual selection and human reproductive behaviour (8+ 16 marks) (NB make sure you link the evaluation of the studies to the theory. You must show that you can evaluate the methodology of studies and explain the impact that this has on our
acceptance of the theory)
3a. Outline evolutionary explanations of human reproductive behaviour (8 marks) A01 POINTS ONLY!
3b. Use research evidence to assess the influence of evolutionary explanations on sexual selection and human reproductive behaviour (16 marks) A02 POINTS ONLY!!!
NB: IN ORDER TO REACH THE TOP BAND FOR A02 MARKS – YOU MUST USE MAID EFFECTIVELY. THIS MEANS LINKING YOUR POINTS TO THE QUESTION, CONTEXTUALISING YOUR ANSWERS BY GIVING EXAMPLES AND USING ISSUES AND DEBATES THROUGHOUT YOUR WORK – DO NOT
LEAVE THEM UNTIL THE END OF YOUR ESSAY.
For any question that states: Explain, Describe, Outline – this is purely A01 material. DO NOT use A02 material in a question that purely asks you to outline, describe or explain… (These questions will range in marks from 4 – 8 marks)
Any question that states: Evaluate, Assess the importance, consider the extent… - this is purely A02 material. Use research evidence to support or contradicts theories and LINK IN MAID THROUGHOUT AND LINK TO THE QUESTION (These could range from 5-16 marks)
If the question states “DISCUSS” – this means A01 AND A02 points throughout (8 + 16 marks, 4 + 8 marks)