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The Nature of Sexual Selection:
Inter- and Intra-sexual Sexual:
An important feature of natural selection is that males tend to be more brightly coloured
than their female counterpart's e.g. the tale of a male peacock. Hence, why would such
disadvantageous traits be natural selected?
Darwin developed a theory of sexual selection, with two processes to explain this;
Intrasexual Selection (mate competition): Members of one sex, usually males, compete
with each other to gain access to the opposite sex. Those who win are able to mate and
pass on their genes. Hence, whatever traits lead to success of gaining access to the
opposite sex, are passed on to the next generation.
Intersexual Selection (mate choice): This involves preferences of one sex who prefer
certain qualities in the opposite sex. E.g. if females prefer tall males, then there will be an
increase in the tall population, therefore making this area more competitive. Hence
preferences determine areas where the opposite sex must compete e.g. in terms of
plumage or economic resources for humans. Human beings are `pre-programmed' to
spot these important indicators, making them more eager to find and mate with those
individuals who possess them.
The reasoning behind sexual selection is that random mating is stupid mating. It costs to be
choosy as low-quality mates can lead to unattractive and unhealthy offspring, whereas
high-quality mates can lead to attractive and higher quality offspring as their genes are much
more likely to be passed on.
Female mate choice varies across the menstrual cycle:
A female may choose a more feminised appearance suggesting kindness and cooperation in
parental care, or a more masculine appearance when conception is likely. Such males are
likely to have higher levels of testosterone which suppresses the immune system. Despite
this, a healthy male must have a highly efficient immune system as it is a very valuable
characteristic to pass on.
Short-term mating preferences:
Humans have different mating strategies, specifically for short-term mating success. Men
have a greater desire for casual sex or seek sex earlier in a relationship. Females would not
be subjected to the same evolutionary pressures.
The less time it takes for the male to have sexual intercourse, the more women he can
impregnate in a given time.
Men often lower their standards for short-term mating opportunities and then show a
decrease in attraction after sex, which is an evolved adaptation in order to bring about a
hasty departure preventing them from spending too long with one woman.
Long-term mate preferences:
In long-term mating both sexes invest heavily in their offspring. Hence, why sexual selection
should favour high levels of choosiness in both sexes.
Poor long-term mate choice could be disastrous from both sexes because they could
potentially waste valuable resources. Women are particular about their mate choice as they
have an obligatory biological investment in their children.
But people don't give away their resources indiscriminately, thus males are likely to choose
females who show signs of fertility.
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Sex Differences in Human Mate Preferences: Buss's Study
The finding of men having preferences for younger women as their partner is consistent with
the theory of sexual selection, because the younger the woman, the greater the fertility.
However, some say that this specific preference is due to power as young women are more
easier to control, and therefore are more desired as mates.…read more
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Sexual Selection…read more