Sexual selection + human reproductive behaviour
Sexual selection = evolutionary explanation of partner preference. Attributes or behaviours that
increase reproductive success are passed on and may become exaggerated over succeeding generations
of offspring.
e.g. advantageous characteristics such as greater height, certain facial and bodily features etc.
Human reproductive behaviour = behaviours that relate to reproduction and therefore increase chance
of survival of our genes.
Anisogamy
= difference between male and female gametes (sex cells):
Male gamete = sperm – very small, mobile, vast numbers created from puberty to old age
Vs.
Female gametes = eggs – larger, stationary, limited number present at birth, limited fertile years
The consequence of anisogamy for mate selection is that there is many fertile males and few fertile
females.
It also gives rise to 2 different mating strategies, leading to 2 types of sexual selection:
1. Inter-sexual selection = between sexes
2. Intra-sexual selection = within each sex
Inter-sexual selection
preferred strategy of females – quality over quantity.
Ova/eggs are rarer than sperm + require more energy, and females invest more time,
commitment and resources to her offspring than males.
This means optimum mating strategy is to select a genetically fit partner who can provide
resources
Runway process in the ‘Sexy sons’ hypothesis (Fischer) = a female mates with a male who has a
desirable + ‘sexy’ trait is inherited by her son so that females will want to mate with her son.
Intra-sexual selection
Preferred strategy of males – quantity over quality: tries to mate with as many females as
possible
= competition between males to mate with a female
The winner gets to pass the successful characteristics to his offspring
Sexual selection = evolutionary explanation of partner preference. Attributes or behaviours that
increase reproductive success are passed on and may become exaggerated over succeeding generations
of offspring.
e.g. advantageous characteristics such as greater height, certain facial and bodily features etc.
Human reproductive behaviour = behaviours that relate to reproduction and therefore increase chance
of survival of our genes.
Anisogamy
= difference between male and female gametes (sex cells):
Male gamete = sperm – very small, mobile, vast numbers created from puberty to old age
Vs.
Female gametes = eggs – larger, stationary, limited number present at birth, limited fertile years
The consequence of anisogamy for mate selection is that there is many fertile males and few fertile
females.
It also gives rise to 2 different mating strategies, leading to 2 types of sexual selection:
1. Inter-sexual selection = between sexes
2. Intra-sexual selection = within each sex
Inter-sexual selection
preferred strategy of females – quality over quantity.
Ova/eggs are rarer than sperm + require more energy, and females invest more time,
commitment and resources to her offspring than males.
This means optimum mating strategy is to select a genetically fit partner who can provide
resources
Runway process in the ‘Sexy sons’ hypothesis (Fischer) = a female mates with a male who has a
desirable + ‘sexy’ trait is inherited by her son so that females will want to mate with her son.
Intra-sexual selection
Preferred strategy of males – quantity over quality: tries to mate with as many females as
possible
= competition between males to mate with a female
The winner gets to pass the successful characteristics to his offspring
