Sexual selection is an evolutionary explanation of partner preference that involves the
attributes or behaviours that increase reproductive success being passed on and potentially
exaggerated over succeeding generations of offspring. As a result of anisogamy - differences in
male and female gametes – there are two types of sexual selection; intersexual selection and
intrasexual selection.
Stemmed from this, intersexual selection is the female preferred strategy which opts for quality
over quantity due to the ova being more limited than the sperm in terms of fertility and
requiring greater energy to produce. Trivers stated that the female makes a greater investment
and commitment because the consequences of making a wrong choice in a mate are much
more serious for the female than the male due to time restrictions. Therefore, the female’s
optimum mating strategy is to choose a genetically fit partner. It’s this preference that
determines which features are inherited by their offspring. For example, if height is considered
an attractive trait, then over successive generations the male population would have an
increase in tall men due to women producing increasingly tall sons with each generation and
daughters who have a preference for height. This is encapsulated by Fisher with his ‘Sexy Son
Hypothesis’ in which a female mates with a male who has a desirable characteristic and this
‘sexy’ trait is inherited by her son. This in turn, increases the likelihood that successive
generations of females will mate with the offspring.
Alternatively, intrasexual selection is the male preferred strategy which includes choosing
quantity over quality and alludes to the competition between males to be able to mate with a
fertile female. In this competition, size matters, so it is the larger males who have an advantage
and thus are more likely to mate and pass on their desirable characteristics to their offspring
As a consequence of this, men for example have evolved indicators such as strong jaw lines,
high cheekbones and wide shoulders as these are signs of strength and testosterone which are
desirable traits that women will seek.
Evidence for intrasexual selection relates to Clark’s investigation in which strangers were asked
‘I have been noticing you around campus. I find you really attractive. Would you go to bed with
me tonight?’ to which 75% of the men answered yes while all women declined the offer. This
supports the evolutionary theory by suggesting that females are ‘choosier’ then males when it
comes to selecting partners and that males have evolved a different strategy to ensure
reproductive success.
Buss conducted a cross-cultural study over 37 cultures with over 10,000 people on mate
preference. Males reported to prefer younger and physically attractive females while females
sought physically strong and athletic males with an emphasis on resources. Both are therefore
engaging in behaviour that increases reproductive success supporting sexual selection theory.
These findings reflect fundamental human preferences which aren’t primarily dependent upon
cultural influences and can therefore be generalised. However, issues with this research
involves the methodology; self-reports may be inaccurate due to social-desirability bias and
potential translation problems which could have be easily misunderstood across across
cultures. Also, outlining the preferences individuals have aren’t representative of what actually