Sexual selection and human reproductive behaviour:
- Sexual selection - an evolutionary explanation of partner preference. Attributes or
behaviours that increase reproductive success are passed on and may become
exaggerated over succeeding generations of offspring
- Human reproductive behaviour - 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.
- Anisogamy - the difference between male and female gametes. Male gametes are
extremely small, highly mobile and are energetically inexpensive. Female gametes
are relatively large, static, limited and require a huge investment of energy. Gives rise
to separate mating strategies:
- Inter-sexual selection - preferred strategy of the female, quality over quantity. Trivers
1972 emphasises the female makes a greater investment of time, commitment and
other resources. The females optimum strategy is to select a genetically fit partner
who can provide resources to help her. The sexy sons hypothesis (Fisher 1930)
suggests a female mates with a male who has a desirable characteristic and this trait
is inherited by her son, this increases the likelihood that successive generations of
females will mate with her offspring.
- Intra-sexual selection - preffered strategy of the male, quality over quantity. Refers to
the competition between (intra) males to be able to mate with a female. The winner
gets to pass on his characteristics to the offspring that contributed to his victory,
ensuring survival of the fittest. Anisogamy dictates that a males optimum strategy is
to mate with as many females as possible, as this does not require much
reproductive energy to produce sperm, and no responsibility. A behavioural
consequence is the preference for youth and a certain shape as indicators of fertility.
- Research support for preferences related to anisogamy - Buss 1989 carried out a
survey of over 10,000 adults in 33 countries and found that females place a greater
value on resource related characteristics whereas males valued reproductive
capacity. This supports the predictions that partner preferences are derived from
sexual selection theory and that they can be applied across cultures.
- Research support for inter-sexual selection - Clark and Hatfield 1989 found that 75%
of males agreed to the question of “would you go to bed tonight?’’ whereas 0% of
women did. This supports evolutionary theory because it suggests that females are
choosier than males in selecting sexual partners as this is the evolved strategy to
ensure reproductive success.
- Ignores social and cultural influences - Womens greater role in the workplace means
they no longer need to depend on men for resources, Bereczkei 1997 argued that
this social change has consequences for womens mate preferences. Chang 2011
compared partner preferences in China over 25 years and found that some had
changed but others remained the same, corresponding with the huge social changes
in that time. Mate preferences are therefore the outcome of a combination of
evolutionary and cultural influences, any theory that fails to account for both is a
limited explanation.
- Support from waist to hip ratio research - Singh 1993, 2002 found that male
preference is not for body size but the waist to hip ratio. A ratio of around 0.7 is
deemed most attractive. The combination of wider hips suggests fertility but not
currently pregnant.
- Support from lonely hearts research - Waynforth and Dunbar 1995 studied lonely
hearts advertisements in newspapers and found that women tended to offer physical
attractiveness whereas men were offering resources.
Factors affecting attraction - self disclosure:
, - Self disclosure - revealing personal information about yourself. Romantic partners
reveal more about their true selves as their relationship develops. These self
disclosures about one’s deepest thoughts and feelings can strengthen a romantic
bond when used appropriately.
- Social penetration theory - Altman and Taylor 1973 describe social penetration
theory of how relationships develop as the gradual process of revealing your inner
self to someone else. In romantic relationships it involves the reciprocal exchange of
information between intimate partners, as they increasingly disclose more and more
information they gain a greater understanding of each other and become closer.
- Breadth and depth of self disclosure - as both breadth and depth increase romantic
partners become more committed to each other. Alman and Taylor use the metaphor
of an onion as an example of the different layers, the low-risk surface and the high-
risk centre. As the relationship develops you reveal more layers.
- Reciprocity of self disclosure - Reis and Shaver 1988 argue that for a relationship to
develop there needs to be a reciprocal element to self disclosure, as to maintain a
balance between both partners.
- Support from research studies - Sprecher and Hendrick 2004 found strong
correlations between several measures of satisfaction and self disclosure and those
who believed their partners did likewise were more satisfied and committed.
Laurenceau 2005 found that self disclosure was linked to higher levels of intimacy in
long term married couples. Such research examples increase our confidence in the
validity of the theory that self disclosure leads to more satisfying relationships.
- Real life applications - research into self disclosure can help people who want to
improve communication in their relationship. Hass and Stafford 1998 found that 57%
of gay men and women said that the open and honest self disclosure was the main
way they maintained and deepened their committed relationships. Such real life
application demonstrates the value of psychological insights.
- Cultural differences - Tang 2013 reviewed the research regarding sexual self
disclosure and found that men and women in the USA (individualist culture) self
disclose significantly more sexual thoughts and feelings than both men and women in
China (collectivist culture). Self disclosure theory is therefore a limited explanation of
romantic relationships based on findings from western cultures which are not
generalizable to other cultures.
- Self disclosure and satisfaction - the onion metaphor suggests that relationship
breakdown is accompanied by a reduction in self disclosure, however Ducks theory
suggests that couples discuss and negotiate the state of their relationship in order to
save it. These discussions frequently involve deep self disclosure and yet may not be
enough to rescue the relationship.
- Correlation versus causation - much self disclosure research is correlational.
Although it is usually assumed that greater self disclosure creates more satisfaction,
a correlation does not tell us if this is a valid conclusion to draw. There may be other
affecting factors.
Factors affecting attraction - physical attractiveness:
- Physical attractiveness - an important factor in the formation of romantic
relationships. The term usually applies specifically to how appealing we find a
person’s face. There is general agreement within and across cultures about what is
considered physically attractive. There exists an assumption that we seek to form
relationships with the most attractive person available.
- Shackelford and Larsen 1997 - found that people with symmetrical faces are rated as
more attractive. This is because it is a sign of genetic fitness.
- McNulty 2008 - found evidence that the initial attractiveness that brought the partners
together continued to be an important feature of the relationship after marriage.
- The halo effect - Dion et al found that physically attractive people are consistently
rated as kind, strong, sociable and successful. The belief that good looking people
- Sexual selection - an evolutionary explanation of partner preference. Attributes or
behaviours that increase reproductive success are passed on and may become
exaggerated over succeeding generations of offspring
- Human reproductive behaviour - 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.
- Anisogamy - the difference between male and female gametes. Male gametes are
extremely small, highly mobile and are energetically inexpensive. Female gametes
are relatively large, static, limited and require a huge investment of energy. Gives rise
to separate mating strategies:
- Inter-sexual selection - preferred strategy of the female, quality over quantity. Trivers
1972 emphasises the female makes a greater investment of time, commitment and
other resources. The females optimum strategy is to select a genetically fit partner
who can provide resources to help her. The sexy sons hypothesis (Fisher 1930)
suggests a female mates with a male who has a desirable characteristic and this trait
is inherited by her son, this increases the likelihood that successive generations of
females will mate with her offspring.
- Intra-sexual selection - preffered strategy of the male, quality over quantity. Refers to
the competition between (intra) males to be able to mate with a female. The winner
gets to pass on his characteristics to the offspring that contributed to his victory,
ensuring survival of the fittest. Anisogamy dictates that a males optimum strategy is
to mate with as many females as possible, as this does not require much
reproductive energy to produce sperm, and no responsibility. A behavioural
consequence is the preference for youth and a certain shape as indicators of fertility.
- Research support for preferences related to anisogamy - Buss 1989 carried out a
survey of over 10,000 adults in 33 countries and found that females place a greater
value on resource related characteristics whereas males valued reproductive
capacity. This supports the predictions that partner preferences are derived from
sexual selection theory and that they can be applied across cultures.
- Research support for inter-sexual selection - Clark and Hatfield 1989 found that 75%
of males agreed to the question of “would you go to bed tonight?’’ whereas 0% of
women did. This supports evolutionary theory because it suggests that females are
choosier than males in selecting sexual partners as this is the evolved strategy to
ensure reproductive success.
- Ignores social and cultural influences - Womens greater role in the workplace means
they no longer need to depend on men for resources, Bereczkei 1997 argued that
this social change has consequences for womens mate preferences. Chang 2011
compared partner preferences in China over 25 years and found that some had
changed but others remained the same, corresponding with the huge social changes
in that time. Mate preferences are therefore the outcome of a combination of
evolutionary and cultural influences, any theory that fails to account for both is a
limited explanation.
- Support from waist to hip ratio research - Singh 1993, 2002 found that male
preference is not for body size but the waist to hip ratio. A ratio of around 0.7 is
deemed most attractive. The combination of wider hips suggests fertility but not
currently pregnant.
- Support from lonely hearts research - Waynforth and Dunbar 1995 studied lonely
hearts advertisements in newspapers and found that women tended to offer physical
attractiveness whereas men were offering resources.
Factors affecting attraction - self disclosure:
, - Self disclosure - revealing personal information about yourself. Romantic partners
reveal more about their true selves as their relationship develops. These self
disclosures about one’s deepest thoughts and feelings can strengthen a romantic
bond when used appropriately.
- Social penetration theory - Altman and Taylor 1973 describe social penetration
theory of how relationships develop as the gradual process of revealing your inner
self to someone else. In romantic relationships it involves the reciprocal exchange of
information between intimate partners, as they increasingly disclose more and more
information they gain a greater understanding of each other and become closer.
- Breadth and depth of self disclosure - as both breadth and depth increase romantic
partners become more committed to each other. Alman and Taylor use the metaphor
of an onion as an example of the different layers, the low-risk surface and the high-
risk centre. As the relationship develops you reveal more layers.
- Reciprocity of self disclosure - Reis and Shaver 1988 argue that for a relationship to
develop there needs to be a reciprocal element to self disclosure, as to maintain a
balance between both partners.
- Support from research studies - Sprecher and Hendrick 2004 found strong
correlations between several measures of satisfaction and self disclosure and those
who believed their partners did likewise were more satisfied and committed.
Laurenceau 2005 found that self disclosure was linked to higher levels of intimacy in
long term married couples. Such research examples increase our confidence in the
validity of the theory that self disclosure leads to more satisfying relationships.
- Real life applications - research into self disclosure can help people who want to
improve communication in their relationship. Hass and Stafford 1998 found that 57%
of gay men and women said that the open and honest self disclosure was the main
way they maintained and deepened their committed relationships. Such real life
application demonstrates the value of psychological insights.
- Cultural differences - Tang 2013 reviewed the research regarding sexual self
disclosure and found that men and women in the USA (individualist culture) self
disclose significantly more sexual thoughts and feelings than both men and women in
China (collectivist culture). Self disclosure theory is therefore a limited explanation of
romantic relationships based on findings from western cultures which are not
generalizable to other cultures.
- Self disclosure and satisfaction - the onion metaphor suggests that relationship
breakdown is accompanied by a reduction in self disclosure, however Ducks theory
suggests that couples discuss and negotiate the state of their relationship in order to
save it. These discussions frequently involve deep self disclosure and yet may not be
enough to rescue the relationship.
- Correlation versus causation - much self disclosure research is correlational.
Although it is usually assumed that greater self disclosure creates more satisfaction,
a correlation does not tell us if this is a valid conclusion to draw. There may be other
affecting factors.
Factors affecting attraction - physical attractiveness:
- Physical attractiveness - an important factor in the formation of romantic
relationships. The term usually applies specifically to how appealing we find a
person’s face. There is general agreement within and across cultures about what is
considered physically attractive. There exists an assumption that we seek to form
relationships with the most attractive person available.
- Shackelford and Larsen 1997 - found that people with symmetrical faces are rated as
more attractive. This is because it is a sign of genetic fitness.
- McNulty 2008 - found evidence that the initial attractiveness that brought the partners
together continued to be an important feature of the relationship after marriage.
- The halo effect - Dion et al found that physically attractive people are consistently
rated as kind, strong, sociable and successful. The belief that good looking people
