Evolutionary Explanations for Partner Preferences
Sexual selection - Darwin
Sexual selection: A process by which characteristics that lead to reproductive success e.g.
physical attractiveness, intelligence, strength etc. are passed on to offspring through genes.
Human reproductive behaviour: This refers to any behaviours which relate to opportunities to
reproduce and thereby increase the survival chances of our genes. It includes the evolutionary
mechanisms underlying our partner preferences, such as mate choice and mate competition.
Some species possess bodily features that do not appear to offer a survival advantage. The male
peacock has a long and beautiful tail, which makes little sense in evolutionary terms as the bird is
less able to fly and is therefore more vulnerable to predators. However, female peahens choose
males with long and glorious tails as mates. The concept of sexual selection states that bodily
features and behaviours that are prized by the opposite sex will lead to increased
opportunities for mating. Those who possess the feature are likely to have greater reproductive
success and leave behind more offspring. Over time, most members of the species come to
possess these attributes.
It pays to be choosy as the genetic quality of a mate will determine half the genetics of any
offspring. Low-quality mates (e.g. those who are unattractive and unhealthy) will be more likely to
produce unattractive, unhealthy offspring. By joining forces with an attractive, high-quality mate,
offspring are higher quality and an individual’s genes are much more likely to be passed on.
For females, it is quality over quantity. This means being attracted to males who:
1. Are able to invest resources in her and her children
2. Are able to physically protect her and her children
3. Show promise as a good parent
4. Are sufficiently compatible to ensure minimal costs to her and her children
(Buss)
However, males do not give away their resources indiscriminately. Therefore, males would be
most attracted to females who display signals of fertility, an indication of their reproductive
value. For males, it is therefore quantity over quality.
-> Buss's research explored sex differences in long-term mate choices and found universal trends
in male and female preferences.
The evolutionary approach distinguishes between two types of sexual selection:
1. Intrasexual
2. Intersexual
, Intrasexual selection Intersexual selection
(within each sex – such as the strategies (between the sexes – the strategies females
between males in order to be selected) use to select males and vice versa)
- Also known as ‘mate competition’ - Also known as ‘mate choice’
- Preferred strategy of the male - Preferred strategy of the female
- Refers to the competition between - Takes place when members of one sex
males to be able to mate with a female (often females) choose from the
available pool of mates
- In many species, males are larger on
average than females, implying that - Members of one sex evolve preferences
males competed for females by fighting for desirable qualities in potential
in the past, making increased size and mates e.g. females desire men who
weight an advantage for males. had resources etc. This is because
female’s reproductive life is short so
- Successful individuals are able to the best chance of reproductive
mate and so are able to pass on their success for the female is to ensure the
genes – it is the victory that has given survival of a relatively small number
rise to dimorphism in humans, the of offspring.
obvious difference between males and - Men, on the other hand, desire
females youthful females, a sign of fertility, as
men have large amounts of sperm and
- Whatever characteristics leads to remain fertile throughout their lives.
success in these same-sex contests The best way for a man to maximise
(e.g. greater size and strength) reproductive success is to mate as
becomes more widespread in the gene often as possible.
pool by virtue of the reproductive - Members of the opposite sex who
advantage this gives to the winners. possess these characteristics (e.g.
resources, attractiveness) will then
gain a mating advantage.
- e.g. Female stickleback fish choose a
male to fertilise her eggs through a
‘double audition’ - firstly, examines the
nest built by a prospective male, then
he will demonstrate his health and
strength by performing a ‘zig zag’
dance. If both are satisfactory, she will
choose him.
- This process ensures that the female
thoroughly ‘tests’ the male to check
his strength and ability to raise the
young.
A03
Sexual selection - Darwin
Sexual selection: A process by which characteristics that lead to reproductive success e.g.
physical attractiveness, intelligence, strength etc. are passed on to offspring through genes.
Human reproductive behaviour: This refers to any behaviours which relate to opportunities to
reproduce and thereby increase the survival chances of our genes. It includes the evolutionary
mechanisms underlying our partner preferences, such as mate choice and mate competition.
Some species possess bodily features that do not appear to offer a survival advantage. The male
peacock has a long and beautiful tail, which makes little sense in evolutionary terms as the bird is
less able to fly and is therefore more vulnerable to predators. However, female peahens choose
males with long and glorious tails as mates. The concept of sexual selection states that bodily
features and behaviours that are prized by the opposite sex will lead to increased
opportunities for mating. Those who possess the feature are likely to have greater reproductive
success and leave behind more offspring. Over time, most members of the species come to
possess these attributes.
It pays to be choosy as the genetic quality of a mate will determine half the genetics of any
offspring. Low-quality mates (e.g. those who are unattractive and unhealthy) will be more likely to
produce unattractive, unhealthy offspring. By joining forces with an attractive, high-quality mate,
offspring are higher quality and an individual’s genes are much more likely to be passed on.
For females, it is quality over quantity. This means being attracted to males who:
1. Are able to invest resources in her and her children
2. Are able to physically protect her and her children
3. Show promise as a good parent
4. Are sufficiently compatible to ensure minimal costs to her and her children
(Buss)
However, males do not give away their resources indiscriminately. Therefore, males would be
most attracted to females who display signals of fertility, an indication of their reproductive
value. For males, it is therefore quantity over quality.
-> Buss's research explored sex differences in long-term mate choices and found universal trends
in male and female preferences.
The evolutionary approach distinguishes between two types of sexual selection:
1. Intrasexual
2. Intersexual
, Intrasexual selection Intersexual selection
(within each sex – such as the strategies (between the sexes – the strategies females
between males in order to be selected) use to select males and vice versa)
- Also known as ‘mate competition’ - Also known as ‘mate choice’
- Preferred strategy of the male - Preferred strategy of the female
- Refers to the competition between - Takes place when members of one sex
males to be able to mate with a female (often females) choose from the
available pool of mates
- In many species, males are larger on
average than females, implying that - Members of one sex evolve preferences
males competed for females by fighting for desirable qualities in potential
in the past, making increased size and mates e.g. females desire men who
weight an advantage for males. had resources etc. This is because
female’s reproductive life is short so
- Successful individuals are able to the best chance of reproductive
mate and so are able to pass on their success for the female is to ensure the
genes – it is the victory that has given survival of a relatively small number
rise to dimorphism in humans, the of offspring.
obvious difference between males and - Men, on the other hand, desire
females youthful females, a sign of fertility, as
men have large amounts of sperm and
- Whatever characteristics leads to remain fertile throughout their lives.
success in these same-sex contests The best way for a man to maximise
(e.g. greater size and strength) reproductive success is to mate as
becomes more widespread in the gene often as possible.
pool by virtue of the reproductive - Members of the opposite sex who
advantage this gives to the winners. possess these characteristics (e.g.
resources, attractiveness) will then
gain a mating advantage.
- e.g. Female stickleback fish choose a
male to fertilise her eggs through a
‘double audition’ - firstly, examines the
nest built by a prospective male, then
he will demonstrate his health and
strength by performing a ‘zig zag’
dance. If both are satisfactory, she will
choose him.
- This process ensures that the female
thoroughly ‘tests’ the male to check
his strength and ability to raise the
young.
A03
