PSYB30H3 Chapter Notes - Chapter 8: Psychopathy, Human Nose, Falsifiability
2 Mar 2019
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Chapter 8: Evolutionary Perspectives on Personality
Evolution and Natural Selection
Natural Selection
- Natural selection – process by which adaptations are created and change takes place over time
- Survival selection – successful variants come to characterize the entire species; hostile forces of
nature are what impede survival, e.g. food shortages, diseases, parasites, etc.
Sexual Selection
- Sexual selection – evolution of characteristics because they contributed to individual’s mating
success, providing advantage in competition for desirable mates
- Intrasexual competition – members of same sex compete with each other and outcomes gives
winner greater sexual access to members of opposite sex
- Intersexual competition – members of 1 sex choose a mate based on their preferences for
particular qualities; these qualities evolve because people with them tend to have genes passed
on more often
Genes and Inclusive Fitness
- Genes – packets of DNA that are inherited by offspring from parents in distinct chunks
- Evolution operates by process of differential gene reproduction – defined by reproductive
success relative to others; genes of organisms that reproduce more than others get passed
down at a greater frequency than those of people who reproduce less
- Inclusive fitness theory – characteristics that facilitate reproduction don’t have to affect the
personal production of offspring, but can affect survival and reproduction of genetic relatives
too; e.g. if you take a personal risk to save your family member, you are helping them survive
and reproduce, and they will pass on the same genes as you
- To help someone evolve, the cost to your reproduction as a result of helping has to be less than
benefits to reproduction of your genes that reside in your relative; e.g. if helping family member
is going to be twice as beneficial as saving yourself, only then you should do it
Products of the Evolutionary Process
- All living humans are products of the evolutionary process, descendants of long line of ancestors
who succeeded in surviving, reproducing, and helping their genetic relatives
- Evolutionary process acts as a series of filters – in each generation, only a small amount of genes
passes through the filter
- Only 3 things can pass through the filter – adaptations, by-products of adaptations, and noise or
random variations
- Adaptations
o Reliably developing structure in the organism which, because it meshes with the
recurrent structure of the world, causes the solution to an adaptive problem
o E.g. a taste for sweet and fatty foods, preference for specific mates
o Emerges with regularity during course of a person’s life – e.g. mechanisms that allow
humans to see develop reliably; evolutionary approaches are not forms of genetic
determinism so you need environments to develop an adaptation and these can
interfere with the development as well
o Features of an environment must be recurrent over time for adaptation to evolve
o Adaptation must also facilitate the solution to an adaptive problem – anything that
impedes survival or reproduction, or anything whose solution increases the odds of
survival or reproduction
o Special design – features of adaptation are components of specialized problem-solving
machinery
o Efficiency in solving specific adaptive problem, precision in solving it, and reliability in
solving it
o Characteristics that were adaptive in ancestral env – e.g. xenophobia (fear of strangers)
are not always adaptive in modern env, might be vestigial adaptations
- By-products of Adaptations
o By-products of adaptations – things that are not adaptations; e.g. a lightbulb produces
light because that is the function but it also produces heat, which is a by-product
o Evolutionary by-products – incidental effects that aren’t properly considered to be
adaptations; e.g. human nose is adaptation for smelling but as a by-product, we can use
it to hold up our eyeglasses
- Noise or Random Variants
o Evolutionary noise – random variations that are neutral with respect to selection; e.g. in
lightbulb design, there are minor variations in surface texture of bulb that don’t affect
functioning of the design elements
o Neutral variations introduced into gene pool through mutation are perpetuated over
generations if they don’t hinder the functioning of adaptations
Evolutionary Psychology
Premises of Evolutionary Psychology
- Domain specificity
o Adaptations are domain specific because they are designed by evolutionary process to
solve a specific adaptive problem; e.g. you don’t eat the first thing you encounter, you
are domain specific because you look for fat and sweet food
o Different adaptive problems require different solutions – e.g. you can’t use your food
preferences as a general guide to the choice of mates
o Selection tends to fashion at least somewhat specialized mechanisms for each adaptive
problem
- Numerousness
o Ancestors faced many sorts of adaptive problems throughout evolution so we have
numerous adaptive mechanisms; e.g. lots of physiological mechanisms, like a heart to
pump blood, liver to detoxify poisons, sweat glands for thermoregulation
o We also have psychological adaptations – common fears and phobias
- Functionality
o Functionality – our psychological mechanisms are designed to accomplish particular
adaptive goals
o You can’t understand your preferences for certain mates without thinking about the
function of these preferences, e.g. to select a healthy mate
Empirical Testing of Evolutionary Hypotheses
- Hierarchy of levels of evolutionary analysis
- Top of hierarchy is evolution by selection
- Next level is middle-level evolutionary theories – theory of reciprocal altruism, theory of
parental investment and sexual selection, and theory of parasite-host co-evolution
- Theory of parental investment and sexual selection
o Sex that invests more in offspring is predicted to be more choosy about mating partners
o Sex that invests less in offspring is predicted to be more competitive with members of
own sex for sexual access to high-investing sex
o From these hypotheses you can derive specific predictions and test empirically
- Deductive reasoning approach – top-down, theory-driven method of empirical research
