PSYC 305: Evolutionary Perspective

evolutionary perspective

* biologically programmed to engage in behaviours that facilitate survival/reproduction - pass our genes to next generation
* humans reflect behaviours adaptive through evolutionary history
* natural selection, sexual selection, inclusive fitness

natural selection

process by which adaptive behaviours are created and change takes place over time

hostile forces of nature

events that impede survival - food shortage, disease, parasites, predators, extreme weather

* cause adaptations to species

adaptations

mechanisms that inherited solutions for survival and reproductive problems posed by hostile forces of nature - immune system developments

* reoccurring environment always needed
* must facilitate solution to adaptive problem
* special design: efficiency, precision, reliability

adaptive problem

anything that impedes survival or reproduction - solution increases odds of survival or reproduction

byproducts of adaptations/evolutionary byproducts

evolutionary process producing things that are not adaptations - incidental effects

* ex. we use our noses for smelling, but they also hold up glass

evolutionary noise

random variations that are neutral with respect to selection

* neutral variances can keep being passed on if they don’t hinder functioning of adaptations

sexual selection

traits evolved to contribute to individual’s mating success rather than survival

* two forms: intrasexual and intersexual competition

intrasexual competition

members of same sex compete with each other to gain sexual access to mate

* more aggressive so males are more likely to have this

intersexual selection

members of one sex choose mate based on their preferences for particular qualities

inclusive fitness

explains behaviours that seem maladaptive - altruism, self-sacrifice

* help survival in indirect ways

evidence for evolutionary perspective

humans across cultures and non-human primates show similar social behaviours

* attachment, affiliation, coalitions, status hierarchies, competition, emotion expression, sexual jealousy - all promote survival and reproduction
* universal emotions: fear, happy, sad, disgust, anger, surprise - pride?

why are emotion expressions adaptive?

send messages that can save lives of sender and receiver

Is pride adaptive?

it communicates success to others

* appearance:


1. Head/neck tilted slightly back = look above others, approach oriented
2. expanded posture = high status, attention
3. slight smile = social cohesion, individual remains strong within group
* In remote village in Burkina Faso, pride was recognized 57% of the time - more than sadness, disgust, anger, and fear

do people actually show pride expression after winning?

* more people display associated behaviours after winning rather than losing
* consistency across cultures
* those born blind display most of the pride behaviours after winning as well

sex differences

* men fertilize externally = need to invest in their children
* women fertilize internally = need to find mate to provide resources during and after pregnancy (personality is important)
* gender differences lead to source of jealousy - jealousy is also adaptive
* men = sexual jealousy (more stressed about partner having sex with someone else)
* women = emotional jealousy (more stressed about partner having an emotional relationship with someone else)
* Buss, Larsen, Westen, Semmelroth (1992)
* greater the variance in reproduction, more ferocious competition within the sex that shows higher variance - more sexually dimorphic

gender differences in ways we think about sex

* women: more likely to think being in love means also having sex
* men: more likely to think having sex also means being in love
* cognitive load study: women think more like men about sex when under cognitive load
* are different in negativity of different emotions - men find anger more problematic, women find sadness more problematic

the big 5

innate psychological mechanisms/strategies that developed to help solve problems of survival and reproduction - optimum level of traits shifts over time (balancing selection)

* extraversion = social rank, cooperation
* emotional stability = resilience to stress, adaptability
* agreeableness = intimacy/mating, altruism
* conscientiousness = work, trust, dependability
* openness = learning, exploration, versatility

evolutionary approaches and individual differences

* frequency-dependent selection: certain traits are adaptive only if there are also people who have the opposite traits
* environmental triggers: environment is cause of individual differences ex. we all have potential to become neurotic, but it is more adaptive in adverse conditions
* contingencies among traits - expression is contingent on other traits person has
* optimum level of personality trait can vary over time and space

environmental triggers of individual differences

* presence of father figure triggers specific sexual strategies
* absent = bonds are not enduring, early sexual maturation, many partners
* present: enduring relationships, long-term, more trustworthy

heritable individual differences contingent on other traits

evaluating one’s personal strengths/weaknesses - adaptive self-assessments produce stable individual differences

* reactively heritable: secondary consequence of heritable body build
* aggression and cooperation in males

frequency-dependent strategic individual differences

* two sexes exist in roughly equal numbers, which is strategic
* women adopt either a restricted sexual strategy when finding a mate - delayed intercourse, prolonged courtship, or unrestricted mating strategy - seeking man for quality of his genes only
* as a given strategy becomes more common, it becomes less successful, so they shift to fit environment

differential gene reproduction

evolution operated by genes of organisms that reproduce more than others, so they get passed down at greater frequency

* genes to do with survival, reproduction, mating success
* basis for inclusive fitness theory

domain specificity

adaptations designed to solve particular adaptive problem

* specialized processes so ensure survival success
* provide multiple solutions to problems

numerousness

we have evolved a large number of psychological mechanisms to aid in survival

* domain specific - many fears, many mating techniques, many habits

functionality

psychological mechanisms are designed to accomplish particular adaptive goals

key premises of evolutionary psychology

1. functionality
2. numerousness
3. domain specificity

hierarchy of levels of evolutionary analysis

1. evolution by selection
2. middle-level evolutionary theories (parental investment, sexual selection)
3. hypotheses
4. predictions

deductive reasoning approach

top down approach - phenomenon is first observed, theory developed to fit

inductive reasoning approach

bottom-up approach to research

approach to human nature

primary product of evolutionary process - need to belong, helping and altruism, universal emotions

need to belong

* being ostracized from a group has always been extremely damaging - social anxiety is a adaptation to prevent social exclusion
* groups share food and other resources, offer protection and defence from threats, provide mates, contain kin - provide opportunities
* more social interaction is associated with higher self-esteem
* group living has always been very important for human survival

helping and altruism

* direct function of recipients’ ability to enhance inclusive fitness of helpers - more likely to help those who share genes
* shown that individuals of higher reproductive value are helped more than those with lower (younger vs. older people)
* genetic relatedness always been important

universal emotions

* 3 perspectives on emotions:


1. are expressions interpreted in same ways across cultures?
2. emotions are adaptive mechanisms that signal fitness affordances - guide towards goal with conferred fitness, avoid conditions that would interfere with fitness
3. emotions exploit psychological mechanisms of others
* Ekman (1973, 1992): gathered pictures of emotions for people all over the world to name - global agreement on happiness, disgust, anger, fear, surprise, sadness, contempt

limits to evolutionary psychology

1. adaptations are forged over a long time, so we can’t go back in time and determine their precise selective forces
2. lack of knowledge around adaptations
3. modern conditions are different from ancestral conditions
4. competing theories
5. hard to test