Evolutionary explanations Flashcards
What is sexual selection?
Darwin (1871): selection of those characteristics that aid successful reproduction (rather than survival)
Aids evolutions as ancestors have passed on traits that aid survival
What’s an example of sexual selection
Peheans mating with peacocks who have large, extravagant tails as it shows they’re healthy and will benefit their offspring
What is anisogamy?
Difference in sex cells
Men: replenished quickly in large amounts and last until old age
Women: limited number, menopause, requires more energy (child bearing)
what is inter-sexual selection?
Between sexes
Where traits increase attractiveness and/or induce members of the opposite sex t mate with them
What did Trivers suggest about inter-sexua selection?
Highlighted that female Reproduction involves greater investment of time e.g., energy and resources for a child
Whilst men also lose resources, they have other opportunities to mate
Therefore, women need to be sure on the genetics they want to pass down e.g., height (attrative trait)
What did Fisher (1930) say about inter-sexual selection?
‘Sexy son’ hypothesis
Offspring will have a desirable characteristics also known as a ‘sexy’ trait
Makes them more appealing to females which increases chances of reproduction
Why are females who look youthful preferred by men?
As it indicates fertility e.g., narrower waist, rosy cheeks
What is intra-sexual selection?
Within sexes
Where traits allow individuals to compete with members of the same sex for mating opportunities
Men favour quantity over quality to reproduce
Therefore females are ‘choosier’ as there is competition between males
Females don’t need to compete as there isn’t a need to pass on their characteristics
How is diomorphism linked to intra-sexual selection?
As it’s the fact that men and women look very different
As males are chosen by who can pass on desirable characteristics e.g., larger muscles (help with competition)
Why are social and cultural factors a limitation?
changes in social norms
cultural factors, access to contraception
Women have a greater role in society so they’re no longer dependent on men to provide for them
Bereczkei (1997) argue that social change has consequences for women’s mating preferences which may no longer be resource oriented
Therefore its a failed explanation
Why is female choosiness a strength for inter-sexual selection?
Clark and Hatfield (1989) sent male and female students out onto a college campu
They approached students asking “Would you go to bed with me tonight?”
Not a single female agreed
75% of males did, immediately
Supports that females are choosier than males
What research supports intra-sexual selection?
Buss (1989) surveyed over 10,000 adults in 33 countries asking about attributes connected to the evolutionary theory
He found that females placed greater value on resource-related characteristics
Whereas males valued physical attractiveness and youth more than females
Supports predictions of consistent sex differences
