PSYC20009 Lecture Notes - Lecture 6: Tabula Rasa, Evolutionary Psychology, Prosocial Behavior
14 Jun 2018
School
Department
Course
Professor
Lecture 6 - Monday 28 August 2017
PSYC20009 - PERSONALITY & SOCIAL PSYCHOLOGY
LECTURE 6
EVOLUTIONARY SOCIAL PSYCHOLOGY
SOCIAL PSYCH IN THE 21st CENTURY
•History of psychology snapshot;
•Introspectionism
•Behaviorism: mind is what the brain does.
•Cognitive revolution
•Standard Social Science Model (SSSM)
•Blank slate written on by experience
•General purpose psychological mechanisms (e.g., learning, induction, rationality) that
are domain general
•But...Biological revolution?
•Neuroscience
•Genetics
•Recognize the fact that (social) psychological processes are grounded in bodies
•These bodies are the products of evolution via natural selection
•Can we use evolutionary thinking to inform (social) psychological theorizing?
TODAY
•Definitions and the logic of evolutionary thinking
•Evolutionary psychology
•Pro-social behavior (kin and non-kin)
•Mate choice
•Revisiting morality, social influence and intergroup conflict
•Challenges, criticisms and value
EVOLUTION
•Evolution: change in inherited characteristics within a population over successive generations
•Darwinian evolution (via natural selection)
•Three premises:
•Individuals of a species show variation in traits (behavioral, morphological, psychological,
physiological)
•Some of this variation is heritable: some traits will be passed on from one generation to
the next
•Some traits provide benefits in terms of survival and reproductive success (adaptation)
•Consequence: those individuals with greater chances of survival and reproductive success (due
to the possession of adaptive traits), will leave more offspring, and those offspring will tend to
resemble their parents (i.e. inherit their traits)
•Thus certain adaptive traits are selected for
•These adaptive traits increase in frequency in future generations, thus coming to be
widespread within a species
DEFINITIONS
•Some definitions:
•Genotype: the genetic makeup of an organism. The genotype in interaction with the environment
gives rise to...
•Phenotype: physical and behavioral characteristics of the organism, for example its size and
shape, its metabolic activities and its patterns of movement.
•Trait: individual variant of a component of the phenotype
•Eye color is a component of the phenotype, brown eyes are a trait
Lecture 6 - Monday 28 August 2017
PSYC20009 - PERSONALITY & SOCIAL PSYCHOLOGY
•Selection pressure: factor in the environment that impacts the likelihood of survival or
reproductive success
•Fitness: number of copies of a gene contributed to future generations
•Traits that increase survival and (thus potential for) reproductive success (offspring) are said
to increase fitness
•Adaptation (noun): trait that has been selected for due to its impact on fitness
THE LOGIC
•Imagine the following...
•A population of organisms (AAaAAaaaaaAAAaa)
•Some organisms have trait A and some trait a.
•Those with A are more likely to reproduce, because A gives these organisms some survival or
reproductive advantage (i.e., increases fitness) that a does not provide (e.g., makes it easier to
get food, find mates, avoid predators).
•If A is heritable, then it will come to proliferate in future generations of the population, as
organisms with trait A produce more offspring than those with trait a.
•A is thus an adaptation: a trait that has been selected for due to its impact on fitness
EVOLUTIONARY PSYCHOLOGY
•Evolutionary Psychology: application of evolutionary theorizing to understanding human
psychology and behavior.
•Assumptions of EP:
•Mind is not a blank slate...
•Composed of collection of evolved psychological mechanisms (modules)
•Adaptations
•Domain specific
•The Environment of Evolutionary Adaptedness (EEA)
•Summary of selection pressures responsible for a certain adaptation
•Think of the EEA as reflecting hunter-gatherer societies
•Thus adaptations may have been adaptive in the past, but may no longer be so
now
WHAT EP DOES NOT IMPLY
•That all traits are adaptations (EP is not panadapatationist)
•Adaptation: trait that has been selected for due to its impact on fitness
•By-product: trait that is coupled with an adaptation, but was not itself selected for (e.g.,
belly-button as byproduct of the umbilical cord)
•Noise: traits that are not adaptations or by-products
•That organisms are consciously pursuing fitness
PRO-SOCIAL BEHAVIOUR
THE PROBLEM WITH ALTRUISM
•Problem: if evolution tailors organisms to behave in ways that facilitate their own reproductive
success, doesn’t this mean that organisms will be selfish?
•Need to take a ‘gene’s-eye view’
•Selfish genes vs. selfish individuals
•"If you were a gene, what would facilitate your reproduction?”
•If an altruistic behavior happens to increase the !
likelihood that one’s genetic material is passed on to future generations, then such a behavior
will be selected for
•How is this possible?
Document Summary
Today: definitions and the logic of evolutionary thinking, evolutionary psychology, pro-social behavior (kin and non-kin, mate choice, revisiting morality, social influence and intergroup conflict, challenges, criticisms and value. Definitions: some definitions, genotype: the genetic makeup of an organism. Hamilton (1964: inclusive fitness: capacity for genetic information to spread in the population, direct (classical) fitness: number of offspring, indirect fitness: via increasing the classical fitness of others who also share one"s genes, i. e. , kin, but not all kin are equal. Found that people were more likely to receive help from those more related by genetic fitness. Grandparental certainty: add a generation, grandparental investment (laham et al. , 2005, the paternal grandmother might also have daughters who themselves have kids. So she might have more certain investment outlets. Reciprocal altruism: helping non-kin, reciprocal altruism: altruism for non-kin can evolve as long as such altruism is reciprocated (either at the time or at some later date, in the long-run, both helper and recipient benefit.
