Sexual selection - evolutionary explanation

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  • Created by: imanilara
  • Created on: 06-06-16 17:45


  • Sexual selection- physical/behavioural trait that increases the reproductive success of an individual will become more and more common over time.
  • Any trait that increases rep success is passed onto many offspring- trait that reduces rep success is not passed on-dies out
  • For theory to be accepted as an exp - must be genetically determined 
  • sexual selection predicts that due to diff selection pressures on males/females- carry out different behaviours 
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Mate choice AO1

Mate - inter specific sexual selection. 

  • According to theory, males should choose young, healthy, attractive females as this increases their chances of producing healthy offspring + the survival of their genes. 
  • Try and mate w as many females as poss- little biological cost - millions of sperm cells produced every day in testes - ensures that as many genes as poss passed on - women can't- can only have one baby at a time
  • Females should choose males who have resources- to invest in them and their offspring - genes more likely to be successfully promulgated 
  • Male who can invest will help ensure the females survival during pregnancy - ensure resulting child is healthy + has access to resources 
  • Females invest more into offspring -carry them in the stomach, childcare- should be choosier about partners than males 
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AO2 research mate choice

Strength- emperical evidence 

  • Buss 1989-37 cultures found that men value potential partners in terms of their ability to reproduce + care for children- expressed as pref for youth and physical attractiveness 
  • Women value males w characteristics related to resource potential + ambitiousness 
  • Shows a difference in male and female preferences as the theory of sexual selection would predict- strength- but metanalysis- low lev of internal val
  • Contradicting evidence of this study - Sallsbury (2003)- 4 ads 'Female seeks male'- the ad with the most responses was for a woman who was 'financially independent and ambitious'- differs to expectations of male mate choice in sexual selection theory- more hist val than Buss - reflects modern cultural shifts in more equality for women- weakness of the theory 
  • Another problem for the theory - homosexual relationships
  • One study - dunbar 1995- heterosexual women three time more likely to seek resources in a partner than lesbians- coincides w theory bc lesbian relationships are unrelated to rep success which is why sexual selection is not a factor 
  • Doesnt address fact that the existence of homosexual relatinoships cannot be accounted for by evol theory- this beh is contrary to the goal of rep success. 
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Alternate explanation

Researchers such as Buss and Dunbar focus bare on nature side of nature v nurture debate- cultural expectations + social norms could account for the differences rather than evol. This is the idea that we learn thru culture what is deemed as attractive. 

  • Behaviourism eg operant conditinoing could be a mechanism by which we learn this - eg we choose a partner but our family and friends laugh- neg reinforcement- not likely to repeat this type of choice 
  • Some support that mate choice is culturally mediated- eg examples about what is considered attractive varies within cultures- skinny in the west, plumper elsewhere- and from era to era- in the 1920s skinny flappers, 1950s, hourglass figures.
  • Buss' similar findings across cultures could reflect the influence of western media shaping ideas about mate preference 
  • SLT could explain how we pick up these ideas from the media- lesbians less affected by this becasue their choice of partner is already deemed unconventional. 
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Gender bias IDA + EEA presumptive

  • Mate choice and choices relating to sexual variety biologically determined - males choosing younger partners and more variety - seen as a theory that justifies sexual inequality in power+ choice. 
  • Female prefs for resources in men only there bc in most societies this is the best way for them to access more gender equality - but if they had greater financial independence and power would their prefs mirror males? 
  • currently most societies allow males more sexual freedom, but women face punishment when they carry out more sexual promiscuity - this could account for the differences - not evol theory 

based on speculation- presumed knowledge about what was deemed adaptive and preferable - no emperical evidence. Pressures in the modern world would differ greatly from those back then.  ext- if beh controlled by genetic drives- we have larger brains and free will to  not do so!

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