Personality differences. Flashcards
What evolutionary forces keep people from differing too much in terms of design of complex adaptations?
Adaptations must survive sexual reconbination (be scrabled and rebuilt).
So all genomes in interbreeding species must contain all requisite parts.
Parasite theory of sex (Tooby, 1982)
sex evolved to thwart disease-causing micro-organisms.
what is good about sexual recombination?
Sex is a costly way to reproduce, much more than asexual reproduction.
By combining your genome with another person, you forfeit 50% of your reproductive success.
Sexual recombination increases biochemical individuality, helping hosts stay one steo ahead of parasites.
Parasites usually evolve much faster than hosts.
Once the parasite has figured out and ‘picked the lock’, every genetically identical descendant (clone) is vulnerable.
Sexual recombinations ‘changes the locks’.
Penke (2011) discusses four evolutionary explanations for personality variation:
Conditional adaptations (very important) Balancing selection (very important) Selective sweeps (less important) Mutation-selection balance (less important)
Conditional Adaptations:
Refers to phenotypic plasticity.
PP - the idea that the same genotype can lead to different phenotypes if the conditions are different in the env.
These are non-genetic diffs - related to environmental conditions during one’s own lifetime.
Including env of ‘self’ - e.g. your own body.
Genetically identical people may find themselves in very different environments, bodies (in terms of condition), etc.
The optimal strategy may depend on the nature of these conditions.
Conditions affecting the pursuit of long vs short term mating -
How difficult your env is.
Sex ratios.
Mate value (health, attractiveness, status).
Longevity of your life.
Importance of male PI or biparental care (env harshness).
Parasites, disease - if there is a lot in your env, you won’t pursue LTM.
Cultural rules.
Different mating strategies could appear to be stable personality (trait) differences if:
a) The conditions evoking them remained stable, or
b) Their personalities became fixed via developmental calibration, e.g.:
The presence of the father in childhood home seems to influence daughter’s sociosexual development (Belsky et al., 1991). - in the direction of increased sociosexual dev, such as reaching puberty earlier.
Birth order effect - e.g. first borns being more conservative (Salmon, 2018).
Personality can also relate to your own bodily condition.
Formidable men, e.g. more anger prone men - also less egalitarian.
(less in favour of the equitable redistribution of resources within society.
You are more likely to benefit if you are powerful. - less concern for equality.
Some condition-dependent adaptations may also be ‘frequency-dependent’.
Advantageousness of strategy depends on how rare/common it is in the general population.
Balancing Selection:
Another way to generate different personalities.
Genetic differences related to selective env’s that vary over evolutionary time.
Contrast this with condition dependence, which posits that same genomes generate different morphs based on conditions that vary over an individual’s life.
Environments vary in terms of climate, food, predation, parasites, toxins, etc.
Variation must be great enough to prevent any one genetic variant from being driven to fixation.
Environmental uncertainty can select for genetic variation.
Aphids switch from asexual to sexual in the Autumn - adaptation for env uncertainty.
Advantageousness of novelty seeking vs hesitation
novelty-seeking behaviours (related to dopamine receptor gene DRD4).
‘Early bird gets the worm, but the second mouse gets the cheese’.
Advantageousness of novelty seeking vs hesitation depends on the distribution of ‘worms’ vs ‘mousetraps’ (Pinker, 1997).
This could relate to the evolution of ‘openness to experience’ - big 5 dimension.
T&C (1990) on balancing selection
All else equal, it is a worse design than phenotypic plasticity - less flexible, more up to chance.
It is unlikely to result from different complex adaptations. - more likely to result from a genetic ‘switch’.
Switch can turn on/off adaptation, activate/regulate other genes.
human ‘niche construction’
Cultural evolution can happen much faster than biological evolution.
Depends much less on genetic change.
Adaptations that are (at least initially) cultural can interact with biological adaptations.
Fire led to selection for smaller teeth, shorter intestines.
Cultural innovation can change env, and so change the biological selection pressures
why EP can’t ignore culture.
Niche construction is another reason why EP can’t ignore culture.
But, the fundamental reason is that ultimately, culture is 100% generated by the brain, a biological organ.
EP compatibility with cross-cultural variation -
Cultural differences can be? (Tooby and cosmides).
(1) evoked or (2) transmitted
Evoked
Evoked cultural differences are based on facultative adaptations.
Means that they become active in response to certain environmental conditions (deployed when called on).
Cultural similarities result from the same brains being in similar ‘environments’, possibly on opposite sides of the world.
