sexual selection Flashcards
evolutionary explanations of behaviour
-explain humans behaviour in terms of adaptiveness and reproductive success.
-If a behavioural feature had been genetically inherited by one generation from another, it must have a specific value for that species. Eg help human to adapt and survive, or help to mate.
sexual selection
Evolution favours the development of some feature that are attractive to the opposite sex, which make it more likely that the possessor will attract a mate and reproduce.
Attributes or behaviours that increase reproductive success are passed on and may become exaggerated over succeeding generations or offspring.
influences on human reproductive behaviour-anisogamy
-Differences between male and female sex cells
• Sperm vs. Egg
• Small vs. Large
• Quantity
• Energy Expenditure
- Common vs. Rare
-Mating strategies have been developed- inter and intra sexual selection
inter-sexual selection
• Preferred strategy of females
• Ova
• Greater investment → pays to be picky
• Optimum strategy is to select a genetically fit partner who is able and willing to provide resources.
• Leaves the males competing for the opportunity to prove themselves.
• Females desire for a fit male determines what is passed on to offspring e.g. height.
intra-sexual selection
Male strategy - quantity over quality.
The winner of the competition gets to mate and pass on the characteristics that lead to the victory.
Size matters in beating opponent - Physical dimorphism (physical differences between male and females due to genes passed on)
Intra-sexual selection can also have controversial behavioural and psychological consequences.
Anisogamy → Optimal strategy for men is to mate with and impregnate as many females as possible.
Capability to do so with minimal effort and minimal post-natal responsibilities.
consequences of differences
Anisogamy & Inter/Intra - sexual selection
Partner preference
• Females
• Genetically fit partners with “resources”
• Intelligence, creativity, status, ambition, financial prospects.
• Males
• Fertility
• Youth
• Chastity
strength-female choosiness
Female choosiness was illustrated by the study conducted by Clark and Hatfield (1989).
They asked male and female student volunteers to approach opposite sex students individually on a university campus, asking the same question: I’ve noticed you around the campus. I find you very attractive. Will you go to bed with me tonight?’
They found marked gender differences in the responses: 75% of male students agreed; however, not a single female said ‘yes’.
This support evolutionary theory because it suggests that females are choosier than males when it comes to selecting sexual partners and that males have evolved a different strategy to ensure reproductive success.
research limitation-more complex
Mate choice may be more complicated than suggested by this approach.
Research by Penton-Voak et al. (1999) suggests that females’ mate preferences change across the menstrual cycle.
They found that females preferred a partner with strongly expressed masculine features during their fertile period, but showed more preference for a partner with slightly feminised features as a long-term mate. This may be because masculine appearance suggests a healthier immune system, which would be advantageous to pass to offspring, while slightly feminine features suggest kindness and parental cooperation - very desirable traits in a long-term partner!
These finding suggest that mate choice may actually be based on a range of factors, rather than simply indicators of genetic fitness.
research support-preferences based on anisogamy
Partner preference was supported by research conducted byBuss (1989).
He conducted surveys in over 33 countries and 10,000 adults and asked questions relating to ages and attributes that evolutionary theory predicts should be important for partner preference.
He found that women placed greater value on resource related characteristics such as good financial prospects, ambition and industriousness than men did. Whereas males valued reproductive capacity in terms of good looks, chastity and preferred younger mates
These findings reflect sex differences in mate strategies due to anisogamy. They support predictions about partner preference derived from sexual selection theory.
Furthermore, the findings can be applied across vastly different cultures, reflecting fundamental human preferences which are not primarily dependent on cultural influences.
