Psychology A2: Human Reproductive Behaviour


Sexual Selection: Inter and Intrasexual Selection

  • Intrasexual selection: Members of one sex compete with the same sex for a mate.   Whatever traits lead to sucess it will be passed onto the next generation. MATE COMPETITION.
  • Intersexual selection: Members of one sex show preferences to certain characteristics which makes the opposite sex more attractive as a potential mate. MATE CHOICE.


Male Preferences: Male preferences for younger women may be due to 'social power'and the ability to easily control. However KENRICK ET AL. suggests that teenage males are attracted to older women. 

Buss found that men do indeed choose younger women and statistics support this when men divorce and remarry signifcantly younger women.

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Sexual Selection: Short Term Mating Preferences

Short Term: Parental investment theory claims that men evolved greater desire for casual relations and would seek sex earlier.

Buss analysed that males were more likely to drop their standards when looking for a short term partner and showed a significant decrease in attraction afterwards.


  • Clarke and Hatfield: Reaserch support for Buss' theory when analysing psychological mechanisms in college students sexual behaviour.
  • Gender Bias within the Theory.
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Sexual Selection: Long Term Mate Preferences

Sexual selection should favour high levels of selectiveness in BOTH sexes. Poor selection could lead to disadvantageous termination.


  • Obligatory biological investment to their children.
  • Women are attracted to: resources, protection, parental instinct and minimal costs to her offspring.


  • Men are attracted to signals of fertility, reproductive value, youth and physical attractiveness.


  • Research support for universal sex differences. Buss' study in 37 cultures supports the values indicated above.
  • Mate choice varies in the menstrual cycle: Mate choice is not constant between short and long term relationships.
  • The importance of Fertility: Miller et al and the menstrual cycle.
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Sexual Selection: Maternal Investment

  • Female investment is greater than the male contribution.
  • Males can opt to remove themselves from the offspring unlike the mother who had carried the child for 9 months.
  • Human females invest more because infants are relatively helpless and are entirely dependant on their mothers for survival due to their early stages of development.
  • Costs of maternal investment makes random mating costly for females. 


  • Greater investment may lead to search for 'good genes' through extramartial affairs. They have the partner who brings the resources and then infidelity lead to those who provides the genes for the best offspring possible.
  • Cuckolding male partners carries risks e.g. abandomment or violence.
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Sexual Selection: Paternal Investment

  • Males invest less as risks related to indiscriminate mating are lower than they are for females.
  • Males also must protect themselves from cuckoldry and therefore are more concerned with sexual infidelities in their female partner.
  • Sexual jealousy may have evolved as a solution to the possible problem of cuckoldry.
  • To protect themselves from possible cuckoldry and infidelity they may use mate retention strategies. 
  • Due to this risk, grandparents also appear to invest more on the maternal side.


  • Reid: This psychologist found that when human males invest and successfully reproduce it leads to a decrease in infant mortality rates due to adequate resources. - is this an old fashioned view? or not a universally applied view?
  • Non Human Insights: Parental investment may be a contribution from cultural learning as chimpanzees and bonobos do not emotionally invest themselves in their offspring.
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