Sexual Selection

Question 1

Who came up with the idea of sexual selection?

Answer 1

Darwin

Question 2

Explain what natural selection is

Answer 2

Darwin explained evolutionary change in terms of natural selection.

The process whereby organisms better adapted to their environment tend to survive and produce more offspring

–> A characteristic that increases an individual’s ability to reproduce successfully must be highly adaptive and those with these genes will go on to produce successive generations, whilst weaker genes will die out

Question 3

What are the problems with natural selection?

Answer 3

Some species have evolved characteristics that are positively detrimental to their survival, such as stags’ antlers and peacocks’ tails

Question 4

What did Darwin come up with after natural selection to overcome the problems?

Answer 4

Sexual selection

Question 5

Explain what is meant by sexual selection

Answer 5

The evolutionary explanation describing why humans prefer some partners over others

Men and women attempt to maximise their chances of reproduction (since reproduction is more important that survival)

We consider what we need from the opposite sex

Question 6

What is sexual selection

Answer 6

A key part of Darwin’s theory explaining how evolution is driven by competition for mates, and the development of characteristics that ensure reproductive success

Question 7

What is sexual dimorphism?

Answer 7

The condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs.
The condition occurs in many animals and some plants.

Question 8

Explain what is meant by sexual dimorphism?

Answer 8

• In many species, males have characteristics (e.g. brighter colouration or exaggerated tails) that serve to attract females.
• Suggests that males are competing for the attention of females.
• Suggests that, in many species, females do the choosing.

Question 9

What is anisogamy?

Answer 9

• The difference between sex cells.
• A type of reproduction where gametes of 2 sexes are dissimilar (in terms of size and number).
• Important for partner preference as gives rise to 2 different mating strategies

Question 10

Explain anisogamy in terms of humans

Answer 10

Males
- Produce millions of sperm
- Very little cost
- So their best strategy is to mate with as many females as possible to produce the maximum number of offspring.

Females
- Produce 400 eggs in a lifetime.
- Huge biological cost during pregnancy and breast feeding.
- So their best strategy is to be very discrimating and more selective as need good genes.

Question 11

What is intrasexual selection?

Answer 11

• Mate competition
  (i.e. between males for females).
• Means the male who wins can pass his genes on to the next generation.
• Can lead to aggression (towards other men for a woman, and to women with child (bc of sex with others)).
• Male preference for youthful and fertile women (leads to reproductive success) and good hip:waist ratio.

Question 12

What is intersexual selection?

Answer 12

• Mate choice
• The female is choosing which male to mate with.
• Women look for traits in a man that they want their son to have (sexy sons hypothesis)

Question 13

Outline short-term mating preferences for sexual selection

Answer 13

• We possess a range of mating strategies evolved for short-term mating success.
• According to parental investment theory, men evolved a greater desire for casual sex, and would ideally seek sex earlier in a relationship.

Question 14

What did Buss (07) say about short-term mating for sexual selection?

Answer 14

Over the period of a year, a man who managed to impregnate a large number of females would have passed on more copies of his genes than a less successful male - but female who had sex with the same number of males in a year is likely to produce only one child - the less time a man permits to elapse before he has sexual intercourse with a woman, the larger number of women he can impregnate in a given time

Question 15

What did Buss & Schmitt (93) say about short-term mating for sexual selection?

Answer 15

In contrast to women, men appear to lower their standard in the context of short-term mating - they also show a marked decrease in attraction following sex - evolved adaptation to bring about a hasty departure which prevents them spending too long with one woman.

Question 16

Outline long-term mating preferences for sexual selection

Answer 16

Both sexes typically invest heavily in any offspring so sexual selection favours high levels of choosiness in both sexes - as women have an obligatory biological investment in children, predicted to be very particular about their choice of mate, however males are also choosy.

Question 17

What does Buss (03) say about long-term mating preferences for sexual selection?

Answer 17

Females are attracted to males who are able to invest resources, able to physically protect and show promise as a good parent

Question 18

Name 3 evaluative points for sexual selection

Answer 18

+ Evidence supporting sexual selection pressures through evolution.
+ Evidence supporting the idea females are more selective.
- Evidence suggesting it’s incorrect that patterns still have strong evolutionary basis.

Question 19

+ AO3 - Evidence supporting sexual selection pressures through evolution.

Answer 19

• Research by Singh (1993) suggests that there are some sexual selection pressures which have been
  constant in terms of evolution and in terms of modern times
  ~ E.g. the hip to waist ratio
• If this ratio is around 0.7, then this demonstrates to potential mates that
  the female is fertile and able to carry children over a long period of time.
• Birth easier when
  the female has larger hips and a narrower waist.
• Therefore, this suggests that some evolutionary
  pressures are still relevant in modern times.

Question 20

+ AO3 - Evidence supporting the idea females are more selective.

Answer 20

• Evidence by Clark and Hatfield (1989) supports the idea that females are more selective when it comes to
  potential mates.
• Due to their greater energy and genetic input into the pregnancy and care for the
  child.
• These researchers found that 75% of college
  males, compared to 0% of females, would be willing to sleep with a stranger if this stranger had
  approached them and complimented them!
• This supports the idea that men have an evolutionary predisposition to want to impregnate as many women as possible.
• This due to the high rates of sperm
  production and little energy/resources required to do so.
  Also supports the differences in mate selection strategies used by females and males i.e. intra- and inter-selection.

Question 21

• AO3 - Evidence suggesting it’s incorrect that patterns still have strong evolutionary basis

Answer 21

• Evidence by Chang et al (2011)
• Suggests it’s incorrect to assume current reproductive patterns still have a
  strong evolutionary basis
  ~ an interactionist approach would be more accurate –> where the
  influences of both culture and evolution are combined together.
• Changing social and cultural norms means women no longer place a large emphasis on
  resource-availability when looking for a new partner (as suggested by Bereczkei et al in 97).
  ~ women are now more financially independent, with the average age of marriage currently exceeding
  30.
• This suggests that some evolutionary pressures for inter-sexual selection no longer apply in the
  modern climate.

Question 22

Explain males’ preference for younger women for sexual selection

Answer 22

• More likely to be fertile
• Female reproductive value peaks and declines relatively early in life.

Question 23

Explain mate-choice in real life for sexual selection

Answer 23

• Good waist:hip ratio
• Nurturing characteristics )to be good mother)
• Youthfulness (fertility)
• Good genes - symmetrical face

Collectivist cultures
- Chastity
- Domestic

Individualistic cultures
- Shared child care
- Less worried about chastity

Question 24

Explain gender differences in short-term mating strategies for sexual selection

Answer 24

• Men generally relax their mate preferences in short-term mating, whereas women increase their selectivity in short-term mating, especially for physical attractiveness.
• Men also prefer short-term mates who are easily sexually accessible.

Question 25

Explain one I&D point about sexual selection

Answer 25

• Gender bias
• Darwin’s established theory of sexual selection suggests women are selective (choosy) in terms of mate selection.
• These views have only recently been challenged by DNA evidence suggesting that women are equally as competitive as men when the need arises.
• Reductionist ?
• Simplistic view of mate selection.

Question 26

Outline Clarke & Hatfield (1989)

Answer 26

• Male and female psychology students asked to approach fellow students of Florida State Uni (of the opposite sex).
• Ask them for one of three things:
  ~ To go on a date
  ~ To go back to their apartment
  ~ To go to bed with them
• About 50% of both men and women agreed to the date.
• 69% of the men agreed to visit the apartment.
• 75% men agreed to go to bed with them.
• Only 6% of women agreed to the apartment.
• 0% women agreed to sex.

Question 27

Outline Singh (1993)

Answer 27

• Studied preferred waist-to-hip ratio as a sign of female fertility.
• Studying the measurements of waist-to-hip ratio of the winners of the Miss America contest for a decade.
• She found that men generally found any waist and hip sizes attractive, as long as a ratio between them is about 0.7.
• A female having larger hips and a slim waist achieves this ratio, and men unconsciously interpret this as a sign that the woman is fertile but not currently pregnant.

Question 28

Outline Waynforth and Dunbar (1995)

Answer 28

• Researched ‘lonely hearts’ columns in American newspapers.
• Discovered that women tended to describe themselves in terms of physical attractiveness and youth (‘exciting, flirty, curvy’).
• Men, on the other hand, advertised their resources and intelligence more than women did.

Question 29

Outline Buss (95)

Answer 29

• Males have much less certainty than females that the child they are raising is theirs.
• This fact can explain the difference in jealousy between males and females:
  ~ Males tend to be more jealous of their partner’s sexual infidelity, because this could result in raising someone else’s child.
  ~ Females are more jealous of their partner’s emotional infidelity, as this may result in withdrawing of resources from the female and the child and puts the child’s survival at risk.
• This idea was supported by Buss et al. (1992): m
  ~ Male students showed greater distress (measured by galvanic skin response) when asked to imagine partner’s sexual infidelity.
  ~ Women were more distressed by thoughts of emotional infidelity.

Question 30

Outline the procedure of Buss (1989)

Question 31

What are the 5 questions asked in Buss (1989)?

Question 32

What are the 4 findings of Buss (1989)?