relationship between sexual selection and human reproductive behaviour - evolutionary explanation Flashcards
AO1 - intro
- Being able to have sex and pass on your genes is obviously the most essential factor in the survival and evolution of the human race.
- According to evolutionary psychologists, whatever pressures our ancestors faced still affect our behaviour today.
AO1 - Short term mating Preferences (casual sex)
- The more females a male manages to impregnate, the greater his reproductive success or in psychological terms we use the phrase “reproductive fitness”. - biologically programmed to sow their seeds
- However, the consequences of casual sex are greater for a woman who may be left pregnant with ‘poor quality’ offspring and no partner, reputational damage etc.
- This leads to very different approaches to casual sex… Men engage in it, and women don’t (because the costs are too high)
- Furthermore, “anisogamy” (differences between male and female sex cells) can explain why women are less likely to engage in casual sex in comparison to men:
- Female gametes (eggs) are less numerous and more costly to produce than male gametes (sperm)
- A woman produces one egg a month but a man can produce billions of sperm in one ejaculation
- A female can only have a limited number of offspring - men can have an unlimited number.
AO1 - reproductive fitness (Short term mating Preferences - casual sex)
- So for men, to maximise their “reproductive fitness” in evolutionary terms they need to have as much sex as possible- many short-term partners.
- However, for women, reproductive success means finding one man who will give her children and stick around to support them long term. - biologically programmed for one monogamous relationship
what are the AO3 points for Short term mating Preferences
- Clark + Hatfield
- Buss + Schmitt
expand on the AO3 point, Clark + Hatfield (short term mating preferences)
- Clark and Hatfield (1989) found significant sex differences in males’ and females’ motivation for casual sex.
- Attractive male and female researchers approached total strangers on a university campus and asked if they would like to go back to their apartment and have sex.
- None of the females agreed, however a staggering 75% of the males did.
- This is evidence that men have evolved psychological mechanisms to ensure success in short-term mating.
expand on the AO3 point, Buss + Schmitt (short term mating preferences)
- Found men show a marked decrease in attraction for their ‘casual partner’ following sex.
- This is allegedly an evolved adaptation which prevents men ‘wasting’ valuable time with one woman, so they can go and basically sow their seeds as much as possible!
AO1 - sexual selection
- Anisogamy and reproductive fitness therefore massively effect male and female attitudes to sex.
- It also hugely effects the strategies they take in terms of choosing a partner- and has given rise to two particular types of selection:
- Essentially… Men COMPETE and Women CHOOSE
AO1- Sexual Selection:
Inter- and intra- sexual selection
- An important feature of most species is that males are more brightly coloured than their female counterparts; the classic example of this is the peacock’s tail.
- You would expect such disadvantageous traits (attracting predators!) NOT to be naturally selected (because they make death more likely!)
- To explain this, Darwin (1874) proposed his theory of sexual selection, which explains that reproductive success must have been enhanced through such features:
- Intrasexual selection (male competition)
- Intersexual selection (mate choice)
AO1 - sexual selection: Intrasexual selection (male competition)
- Intra = a = among the same sex
- Members of one sex (usually males) compete with one another for members of the opposite sex. The victors are able to mate and so pass on their genes, where as the losers cannot.
- Whatever traits lead to success in these same-sex contests will be passed on to the next generation.
AO1 - sexual selection: Intersexual selection (mate choice)
- Inter = between the sexes
- This form of selection involves the preferences of members of the opposite sex who possess certain qualities.
- For example, if females prefer tall males, over time there would be an increase in the number of tall males in the population.
- The preferences of one sex therefore determine the areas in which the other sex must compete.
what are the AO3 points for sexual selection
- Buss
- Ultimate VS. Proximate Causes
- Alpha bias
expand on the AO3 point, Buss (sexual selection)
- Studied over 11,000 people from 37 cultures across the world
- Wanted to explore whether there were universal mate preferences
Results:
- There were indeed universal mate preferences. Across all cultures women wanted men who had resources or at least traits that would translate to resources (ambition, intelligence)
- Men across all cultures desired a woman younger than them (average age 25- prime reproductive age) with an hourglass figure (indication of fertility)
- This shows support for evolutionary explanations of sexual behaviour. The fact that the same preferences existed everywhere, regardless of culture, indicate that sexual selection is an innate, natural mechanism and not one affected by nurture.
expand on the AO3 point, Ultimate VS. Proximate Causes (sexual selection)
- In the EEA, for women engaging in casual sex this would have been a huge risk, as they would no doubt have been left as single mothers.
- However, NOW we have CONTRACEPTION which of course reduces the risk of pregnancy and therefore fundamentally ALTERS female sexual behaviour.
- Women can now engage in just as much casual sex as men without fear of the consequences of pregnancy.
- For this reason, we have to ask ourselves- are certain aspects of sexual selection theory STILL applicable to current human reproductive behaviour?!
expand on the AO3 point, Alpha bias (sexual selection)
- This area of psychology is also hugely alpha biased.
- This is where psychologists MAXIMISE the difference between the sexes i.e. in this case men are viewed as uncaring irresponsible people who only wish to sleep around and father children without actually being a father, whilst women are viewed as monogamous, caring, responsible mother figures.
- In reality we know that this is not the case at all.
