Genetics & Evolutionary Foundations of Behaviour (unit 3-grey)

psychology

Purpose of Behaviour Genetics

• identify individual differences

• roles of heredity (nature) & enviorment (nuture)

Genes

= segments of DNA, contain info to build proteins/reg other genes

• chromosomes (contains DNA w code for protein) inside nucleus (23 pairs, 46 total)

• every cell has same set of chromosomes (not sex)

Genes Analogy

• protein = cake

• gene = ingredients

• dna = recipe

• chromosome = book binding

Proteins

• building block/machinery of cells (help: ion channels, enzymes, etc)

• differences in DNA sequence in gene/how its read → diff structure/function of protein 

Genotype v. Phenotype

G: inherited genes
P: observable phys/behavioural traits

Adoption Studies? Twin Studies 

• adopted child more sim to biolgoical parents = nature has greater influence 

• more sim to adoptive parents = nurture

twins: manipulate nature + hold nurture constant (vice versa) 

Natural Selection

• competition for survival b/w individuals in a species 

• individuals differ in ability to survive/reproduce in particular enviorment 

• adaptive traits become more common in pop 

Sources of Genetic Variability for Natural Selection

• reshuffling of genes during reproduction

• mutations (errors during DNA replication)

Epigenetics

how behaviours/enviorment can change gene function (wo altering DNA sequence)

DNA Methylation

• methyl group can attach to DNA

• can activate/repress gene (cant uncoil/be read)

Artifical Selection

• selective breeding produces genetic changes in pop

• humans decide traits that are adaptive & should be passed

Natural Selection as Foundation For Functionalism

• william james 

• explain behaviour by what it accomplishes for individual

• tries answering how traits helped ancestors survive/reproduce 

Evolutionary Psychology

• studies why humans are alike 

• suggests human mind is composed of mental adaptions that functioned to benefit survival/reproduction of early ancestors 

Possible Psychological Adaptations

• facial expressions (esp neg)

• delvop fears of natural dangers 

• langauge use 

• perfering potential mates (health/fert)

Mating Systems: Polygyny

• societies w low M/F ratios (men w many women)

• high competition for resources

Mating Systems: Monogamy

• most common

• equal parental investment

Mating Systems: Polyandry

• least common (woman w multiple hubbies)

• societies w scarce enviormental resourses

• aim: limit pop growth & enhance child survival

Mating Systems: Promiscuity

• investment in group (animals)

• not perferred by humans 

Sex Differences

F: cost of reproduction higher,reproduce for short period, more choosy (value: resources to help raise offspring) 

M: reproduce longer, (value: fertility → young/attractive) 

David Buss

= sex differences in mate preference criteria, diff cultures

result: 

• women value finnical prospects/ambition more

• both perfer older 

• men value apperance more 

Sex? Gender? Gender Identity? Gender Roles?

• Sex: biologically determined status as M/F (nature)

• Gender: cultural definition of M/F (nurture) 

• Indentity: how person views themself in terms of gender 

• Roles: expectations of how M/W supposed to behave 

Social Learning Theory v. Gender Schema Theory

SLT: learn gender behaviour through → reinforcement, punishment, observation 

GST: conform to cultural idea of how to be F/M

Evolutionary Analysis of Helping/Hurting: Agression

= men more violent

ex reasons: 

• defend against attack 

• negotitating status/power hierarchies 

• deteriring mates from sexual infidelity 

Evolutionary Analysis of Helping: Cooperation

helping (promotes anothers survival/reproduction), 2 forms:

1. cooperation (help others while taking care of self) 

2. acts of altruism (help others at net cost to self) → kin selection theory (help people who look like us, past = helping genetic kin helped ensure our genes passed on)

Naturalistic v. Deterministic Fallacies

N: idea that what is found in nature is good 
D: belief that genes control behaviour in ways that cant be altered by enviormental experiences/conscious decisions 

3 Laws of Genetic Complex Traits 

1. all traits show sig genetic influence 

2. no traits 100% heritable 

3. heritability caused by many genes of small effect 

Interaction of Nature & Nurture

links genes & behaviour

• most behavious involve many genes

• heritability is low (room for other influences)

• personality determined by genetics/enviroment (polygenetic → more than single gene involved)