Evolutionary explanations for partner preferences

• Charles Darwin developed the theory of sexual selection in 1871.
• Sexual selection= the evolution of characteristics that confer a reproductive advantage- this includes being attractive to the opposite sex, fending off competitors for mates & selecting a high quality mate for the purposes of reproduction.
• • Only individuals that have the opportunity to reproduce will pass their genes onto the next generation.
  • The next generation will inherit the characteristics that make reproduction more likely.
  • Over many generations, these characteristics are exaggerated & have shaped modern human reproductive behaviours.
• Reproductive behaviours include: who we find attractive, how we interact with members of the opposite sex, who we choose to have sex with & how we compete with others for access to mates etc.
• The theory of sexual selection can be used to explain gender differences in human reproductive behaviours, such as partner preference or promiscuity.
• One explanation of sexual selection comes from the concept of anisogamy- differences between male & female sex cells:

  • Male sex cells (sperm) produced in large quantities, quickly replenished & created continuously from puberty to old age. Reproductive success for males is based on quality of offspring.
  • Female sex cells (ova) take a lot of energy to produce & created in limited numbers during specific time intervals and their production only lasts for a certain number of fertile years. Reproductive success for females is based on quality & survival of offspring.
• Anisogamy has led to the existence of two types of sexual selection:

  1. Intra-sexual selection
  2. Inter-sexual selection
• Intra-sexual selection:

  • Selection of features that help with beating members of the same sex for access to opposite sex to be passed onto future generations.
  • In most species, it is the males again at each other that compete for access to females- which is why they tend to be stronger, more aggressive, more competitive etc.
• Inter-sexual selection:

  • Selection of features that make it more likely we will be chosen by the opposite sex for mating to be passed onto future generations.
  • Both genders choose their mate, but 'choosiness' tends to be higher in female to ensure that limited chances for reproduction are not wasted- women are attracted to men who can protect & provide for their young.
• Key study- Buss (1989):

  • Was a study into the evolutionary explanations for partner preference.
  • 10,000 people from 37 different cultures. PPs asked to rate each of 18 characteristics (eg physical attractiveness, good financial prospect) on how important they would be in choosing a mate.
  • A 4-point scale was used- ranging from '3' (indispensable) to '0' (irrelevant).
• Key study- Buss 1989- findings:

  • Women more than men desired mates who were 'good financial prospects'- translating into a desire for men with resources, or qualities such as ambition & industriousness.
  • Men placed more importance on physical attractiveness- provides cues to a woman's health and hence her fertility & reproductive value.
  • Men universally wanted mates younger than them- an indication that men valued increased fertility in potential mates.
  • Both sexes wanted mates who were intelligent (skilled in parenting) & kind (linked to an interest in long-term relationships).
• Evaluation for sexual selection- strength:

  • Research suggests universal agreement across cultures in features important in partner selection, ie what we find attractive.
  • Includes findings from Buss study- eg males preferred younger mates, females put more importance on good financial prospects etc.
  • Universally indicates an evolved basis for partner preference, supporting the theory of sexual selection in explaining human reproductive behaviours.
• Evaluation for sexual selection- strength:

  • Is research evidence for gender differences in reproductive behaviours- Clark & Hatfield (1989) asked male & female student volunteers to approach opposite sex students individually on a uni campus, asking the same question: 'I've noticed you around campus, I find you very attractive, will you go to bed with me tonight'.
  • Found gender differences in the responses: 75% male students agreed, but not a single female said 'yes'.
  • Provides support for role of intra-sexual selection- thought to be linked to higher levels of choosiness amongst Fem than Mal
• Evaluation of sexual selection- weakness:

  • Mate choices research might suffer from a serious problem of validity, ie studies such as Buss' survey of mate choices gives us an indication of expressed preferences, rather than being a reflection of what actually happens in real life.
  • Indicates that information gathered from these studies & surveys are not sufficient & valid.
• Evaluation of sexual selection- weakness:

  • Females' preferences for high-status men may not be universal- Buller (2005) argues that the majority of studies attempting to determine female mate preferences have been carried out on female undergraduates who expect to achieve high educational status & expect high income levels.
  • These women may therefore prefer men with similar interests, education & prospects as their own. As a result, Buller concludes that the evidence for universal female mating preference for high-status men is weak or non-existent.