intra-sexual selection Flashcards
intrasexual selection
strategies within each sex to compete and be selected as a mate
what does competition within the genders lead to
the winner can reproduce and the characteristics that led to their success can be passed on
- those with unsuccessful characteristics dont pass on those genes as they arent selected to reproduce with
what has intrasexual selection led to
dimorphism
dimorphism
females and males looking very different
males - larger males are at an advantage (men are about 15% larger than females)
females - dont have to physically compete so are smaller
behavioural consequences of intrasexual selection
males benefit from behaving aggressively to acquire fertile females and protect them from competing males - leads to selection of aggressiveness in males
A strength of intra-sexual selection is that there is supporting evidence from Buss (1988) and
Daly and Wilson (1988).
Buss (1988) found that men are significantly more likely than women to make threats of
violence towards others who were perceived to have made sexual advances towards
their mate. Females, in contrast, are more likely to use verbal aggression towards potential
rivals. Females often target the attractiveness or the sexual conduct of their competitors
in their verbal aggression and appear to aim to reduce their competitor’s attractiveness in
the eyes of the male. Daly and Wilson (1988) found that 90% of all same sex murders involve
men at an age when mate competition is most intense and that a large proportion of this
violence is connected to sexual rivalry.
E: This is a strength because it supports the theory of intra-sexual selection and males
competing with other males leading to violence.
L: Therefore, it provides intra-sexual selection with validity.
A limitation of sexual selection theory is that it cannot explain the partner preferences of gay
men and lesbian women. This is partly because homosexual relationships do not have
reproduction as its primary aim.
Lawson et al (2014) looked at personal ads placed by heterosexual and homosexual men
and women. These ads described what the person themselves was looking for and what
they were offering. They found that the preferences of homosexual men and women differ
just as they do in heterosexual men and women. Men emphasized physical attractiveness
and women emphasized resources.
E: This is a limitation because it seems based on this, homosexual men still prioritise physical
appearance in their parter and homosexual women still pritortise resources even when they
don’t plan on having children.
L: Therefore, evolutionary explanations may not be a valid explanation of all relationships.
A limitation of evolutionary explanations of human reproductive behaviour/partner
preferences is that it is deterministic.
If sexual selection, human reproductive behaviour, and the relationships involved are driven
by purely evolutionary considerations, then they would be highly predictable. However, with
non-heterosexual relationships and the fact that human reproductive behaviour has changed
dramatically over the last century, with widespread use of contraception, and couples
choosing not to have children implies that we have more control (free-will) over our behaviour
than is implied by the evolutionary approach. Gender differences might stem from cultural
traditions rather than being the result of evolved characteristics. The fact that women have
been denied economic and political power in many cultures might account for their tendency
to rely on the security and economic resources provided by men.
E: This is a limitation because it shows that mate preferences are the outcome of a combination
of evolutionary and cultural influences. Evolutionary theory underestimates this impact as it
is based upon genetic factors.
L: Therefore, evolutionary explanations may not be a valid explanation of human reproductive
behaviour and partner preferences.
