6c. Sexual Selection: the biology of human mate choice Flashcards
What is intrasexual competition?
Competition between members of the same sex
Why does intrasexual competition take place?
For access to potential mates via:
territory (e.g. lekking species)
increased desirability
What suggests a clear evolutionary (biological) origin for intrasexual competition?
Positive link between testosterone and competition (increases motivation to compete)
According to evolutionary theory, who is more likely to be competitive and why?
Young males (18-40), as they are most active in mate choice
Where does evidence as to who is most competitive come from?
Scientists, criminals, artists, musicians and writers
Which males have no need to compete?
Married males need to direct resources to partner and offspring (therefore less motivation to compete)
Testosterone in relationships - testosterone levels are affected by…
relationship satisfaction divorce type of marital system (polygamy vs. monogamy) levels of parental care whether it is a 'new' relationship
TRUE OR FALSE: There is no difference in testosterone levels between single males and males in ‘new’ relationships.
True
What is polygamy?
One man has multiple wives at once
How does polygamy affect testosterone levels?
Men who are already married but looking for more wives have high testosterone levels
Example of a country where polygamy is used as a marital system
Kenya
What suggests that testosterone levels in relationships is psychological?
High levels of testosterone in married males who have an affair
Marriage and competition in sport - tennis
Anecdotal evidence that famous male tennis players do not perform as well once they are married
Marriage and competition in sport - Farrelly & Nettle (2007)
Success measured by ATP point accrued per year
Married players’ points were lower the year after marriage compared to the year before
TRUE OR FALSE: New fathers experience an increase in testosterone levels.
False - fatherhood further suppresses testosterone levels, and leads to longitudinal changes (i.e. more time spend with children, lower testosterone)
Testosterone levels and presence of females - research
- testosterone increases in males when interacting with female experimenter (and more so when rated as highly attractive)
- Male skateboarders had higher testosterone and attempted more risky manoeuvres when observed by female
Research - individual differences may link testosterone levels with mating effort
Extraversion (which predicts mating effort) positively correlated with male testosterone levels in a polygynous population in Senegal
What 3 phases does the menstrual cycle consist of?
Menstruation
Follicular
Luteal
What controls the 3 phases of the menstrual cycle?
Complex interplay between different hormones
When is peak fertility in the menstrual cycle?
Between days 6-14 of 28 total
Behavioural changes across the menstrual cycle?
Oestrus present in other mammalian and primate species
Enhances proceptivity and receptivity to males during fertile stages
Why are there no behavioural changes in humans across the menstrual cycle?
Concealed ovulation
How do other animals give away which stage of the menstrual cycle they’re at?
Lordosis reflex:
Lifting of hind quarters for sexual receptivity
Swollen perineum
Bright red in certain primates
According to evolutionary theory, should females’ mating behaviour vary across the menstrual cycle?
Yes…
Increased chance of conception and ovulation
Female choice should be different when chance of conception is highest
Characteristics looked for in partners vary too
What 2 traits does female mate choice select for in males?
Good genes - attractive/healthy offspring
Good parenting - valuable qualities for long terms and nurturing
How does females’ mate choice vary across the menstrual cycle?
Genetic quality is more important at peak fertility (more likely to have offspring who inherit this quality at this stage), especially for short term mating opportunities
How does females’ mate choice stay consistent across the menstrual cycle?
Good parenting qualities are desirable across the menstrual cycle and for long term mating opportunities
Evidence for human oestrus
Possible to examine empirically
Female preferences and behaviour can be examined across the menstrual cycle
Fertility can be assess by self-report
Or actual measures of different hormones e.g. progesterone
Masculinity is a signal of genetic quality in terms of…
physical attractiveness, health, immunocompetence
How do females’ preference for masculine features change during the menstrual cycle?
Prefer males with masculinised FACES, BODIES and VOICES at high fertility, and feminised faces at other times
How do females’ preferences for masculine features change depending on type of mating opportunities?
Preferences are more pronounced for SHORT TERM mating opportunities
How do females’ preferences for symmetrical features change during the menstrual cycle?
Females prefer more symmetrical male faces, bodies and scents at high fertility
How do females’ preferences for creativity and wealth change over the menstrual cycle?
High fertile females preferred creative but poor males over uncreative but rich males
What traits signal good parenting?
Intelligence
Good father
Faithful
‘Warm’ personality
How does creativity signal good genes?
A good brain, high quality and well developed
Does cooperation signal good parenting or good genes?
No effect of fertility levels across menstrual cycle on preference for cooperation –> suggests cooperation signals phenotypic benefits (e.g. kind, good provider, nurturing)
TRUE OR FALSE: Females have greater attraction to males other than their partners during high fertility.
True
TRUE OR FALSE: Females are more committed to their partners during fertile stage.
False: Females are LESS committed to their partners during fertile stage
Commitment to partners is moderated by FA of partner. What does FA stand for? And why is this?
FA = Fluctuating asymmetry
Because of evolved motivation to gain good genes for offspring
Do males pick up on cues of oestrus? Research involving lap dancers
Measured tips earned by lap dancers across their menstrual cycle
Earned nearly $100 more per shift during high fertility
Evidence against preference for masculinity at high fertility
No difference in preference for men with beards (signals masculinity) or facial masculinity across the cycle
Neither masculine bodies or voices vary in attractiveness across menstrual cycle
Evidence against desire for uncommitted relationships at high fertility
No change in desire for uncommitted (i.e. ST) sexual relationships across the menstrual cycle
Example of a cycle effect that still remains, and what does it suggest?
Increased sexual desire at peak fertility
Suggests might be adaptive
