sexual selection and human reproductive behaviour

Question 1

what does anisogamy refer to?

Answer 1

the differences between male and female gametes

Question 2

what are some differences between male and female gametes?

Answer 2

• sperm= small, mobile and continuously produced from puberty to old age
• ova= larger, static and produced at intervals for a limited number of years

Question 3

explain how anisogamy is thought to impact on human reproductive behaviour

Answer 3

the consequences of anisogamy are that there are plenty of fertile males but fewer famles and this gives rise to different mating strategies

Question 4

inter-sexual selection is the preferred strategy of the female- quantity over quality. Explain how

Answer 4

• inter-sexual selection is the selection of mates between sexes e.g. females selecting or males selecting females
• the female makes greater investment of time, commitment and other resources, before, during and after the birth of her offspring = more crucial females are more choosy in term of a mate’s reproductive fitness than it is for males
• both sexes are choosy to some extent about their partner but the consequences of making a poor choice of partner are most serious for the female= pays for her to be especially choosy in terms of inter-sexual selection= females seek a mate that will not only provide healthy offspring but who will support them with resources

Question 5

how do inter-sexual selection factors impact on human reproductive behaviour?

Answer 5

• the preferences of both sexes determines which attributes are passed on
• for example, if height is a genuine marker of fitness in males, the females who choose the tallest males will have greater reproductive success
• their innate preference for tallness is passed onto their daughters who also choose taller men and are more reproductively successful
• over time this leads to taller and taller men being selected
  = RUNAWAY PROCESSS

Question 6

intra-sexual selection is the preferred strategy of the male- quantity over quality. Explain how

Answer 6

• intra-sexual competiton involves males competing with other males
• they have to compete because females are a limited resource and are choosy
• the males who compete successfully are able to pass on their genes to the next generation and therefore those traits that led to their success are perpetuated

Question 7

intra-sexual selection pressures lead to certain patterns of human reproductive behaviour :

Answer 7

1- male aggression: males who act aggressively may be more likely to succeed in mating as they are more likely to win a competition with another male

2- male preference for youthful and fertile women since such characteristics are a better guarantee of reproductive success= the genes of those males with such innate preferences are more likely to be represented in the next generation= successful reproduction strategy

3- male desire to optimise mating chances by fertilising as many females as possible also ensures the passage of such preference genes to the next generation

Question 8

what are the evaluation points for sexual selection and human reproductive behaviour?

Answer 8

• support for relationship between intra-sexual selection and human reproductive behaviour (Buss)
• further support for the relationship between intra-sexual selection and human reproductive behaviour (Clark and Hatfield)
• one limitation is that this relationship ignores social and cultural influences
• support from waist-hip ratio (WHR)preferences of males for females

Question 9

explain how there is support for relationship between intra-sexual selection and human reproductive behaviour (Buss)

Answer 9

• Buss surveyed over 10,000 adults in 33 countries asking about partner preference
• he found that females placed greater value on resource-related characteristics than males did e.g good financial prospects and ambition whereas males valued reproductive capacity e.g. good looks, chastity and youth
• this supports sex differences due to anisogamy and partner preference derived from sexual selection theory
• what’s more, findings can be applied across many cultures!

Question 10

explain how there is further support for the relationship between intra-sexual selection and human reproductive behaviour (Clark and Hatfield)

Answer 10

• Clark and Hatfield sent students onto campus to approach other students with the question: “I have noticed you around campus. I find you to be very attractive. Would you go to bed with me tonight?”
• NO FEMALES DID but 75% of males did
• this supports the suggestion that female choosiness is a reality and males have evolved a different strategy to ensure their reproductive success

Question 11

explain how one limitation is that this relationship ignores social and cultural differences

Answer 11

• partner preferences have impacted over time by changing social norms and cultural practices and have occurred too rapidly to be explained in evolutionary terms
• for example women have a more significant role in most workforces and as such, are less reliant on male resources
• Chang et al report that some preferences have changed and others have remained the same over 25 years in China
• this suggests that both evolutionary and cultural influences must be taken into account when explaining human reproductive behaviour

Question 12

explain how there is support from waist-hip ratio (WHR) preferences of males for females

Answer 12

• Singh measured WHR preference of males for females
• the findings were that any hip and waist size can be attractive as long as the ratio of one to the other is 0.7- this is thought to signify that the female is fertile but not currently pregnant
• this shows that evolutionary factors are reflected in patterns of human reproductive behaviour through partner preferences