Lecture 9 Flashcards
What is the difference between inter-individual variation and intra-individual variation?
Inter is the differences between individuals and intra is the differences within an individual
Discuss the problem evolutionary psychologists have when thinking about characteristics
They tend to think about a characteristic as a whole, and not the differences of that characteristic within a population.
Why are individual differences a problem for evolutionists
Selection pressures should eliminate all but the fittest variations - we should only see the personality types that have the highest fitness and we should NOT see individual differences.
What is differences within a population called?
Polymorphism
What does polymorphism mean
Individual differences within a population
What did Tooby and Cosmides (1990) say about polymorphism?
Any individual differences are irrelevent or push evolution, thus polymorphs should not exist. Small differences are just noise and large differences are selected for. However, there has to be some variation otherwise there is nothing for evolution to select for.
Name and describe three reasons for individual differences
Niche picking or strategic specialization is: if everyone does the same thing, the competition would be too high.
Life history strategies state that we employ a strategy depending on the environment we are in.
Frequency dependent adaptive strategy says our adopted strategies’ success depends on how many others have adopted that strategy.
Discuss Niche picking/strategic specialization
If everyone does the same thing, the competition is too high so personality could reflect different strategies. For example, birth order (sulloway - lecture 5) where the first borns identify more with parents thus the second born have to adopt a different strategy to get the attention and are often more rebellious.
Blue tits are either low in boldness or high in boldness, they both survive as they both do better in different conditions; in males lower boldness do better in good foraging years and the bolder blue tits do better in the bad foraging years. This is because bolder males defend more territories when times are good but engage in unnecessary aggression when food is scarce.
How does niche picking and strategic specialization reflect differences within human personality
Nettle (2006) found the evolutionary function of the extraversion continum. The more extravert males were the more mating success they had, however the more risk they had physically. Similarly females also have greater mating success, but they also have less parenting effort.
Shackleford (2005) discussed evolution personality and recycling: our personalities help us find/keep a mate, avoid conflict and maintain status. However they don’t help us tackle group issues (such as the environment). But we are socially equipped so we can capitalise reciprocal altruism and tackle the free rider.
Discuss life-history strategies
Individual differences may also reflect differences in life history; life hisotry strategies are behaviours or traits that reflect an individuals conditional response to the environment in order to maximise fitness, as not everyone is in the same environment you would expect differences to emerge. The traits are conditional to a particular environment. For example, if females have fathers present they expect their reproductive partners to be around and provide resources, with a focus on parenting. However, females who don’t have a father present expect reproductive fathers to be roaming males and they focus on mating. They also have earlier menarche, earlier first intercourse and earlier pregnancy. (Quilan, 2003). In men, when the father is present their voices tend to break later (proximate stress effects), however when they are absent, they have a higher probability of reproduction by the age of 23.
Discuss frequency dependent adaptive strategies
The success of a variant could be depedent on how many others are like you. In bluegill sunfish, there are three types of males; large, female looking and sneak males. The sneak and female looking males reproduce by fertilising the females eggs as she is unaware they are there, however they wouldn’t be able to do this if the majority of the population was like them, as it would take the sneaky out of it. Similarly, if all the males were large, there would be more fights and more would die allowing for more sneaky males and so on.
Mealey (1995) used this explanation to try and explain psychopathy; if there were more psychopaths we would be able to notive them and counter them, however as there are not many they can get away with it.
Discuss intra-individual variation and ovulation.
Variation within the individual. Ovulation has been the target of most studies on the menstrual cycle. Other mammals all have obvious behaviours and signals associated with sexual receptivity, whereas human ovulation is concealed. However, there are still some differences within a females personality and traits that differ when she is ovulating. For example, they look for masculinity when they are ovulating as they are looking for the best genes. However they look for the more feminine males when they are not ovulating; the ones who will look after their offpsring and provide. As well as this, females are more likely to have a short-term affair with a talented poor man when they are ovulating, and a talentless rich man when they are not.
