Evolutionary Theories in Psychology

These flashcards cover key vocabulary related to evolutionary theories and psychological adaptations as discussed in the lecture notes.

Sexual Strategies Theory

Theory suggesting men and women evolved different mating strategies: Men = short-term, quantity-based Women = long-term, stability-based. These vary with context and culture.

Evolution

Change in inherited traits of a population over time due to natural selection and adaptation.

Natural Selection

Process where organisms with advantageous traits survive and reproduce more successfully, passing those traits to offspring.

Survival Adaptations

Traits that evolved to help ancestors survive environmental challenges (e.g., sweating, shivering, fear of predators).

Reproductive Adaptations

Traits that evolved to help individuals attract mates and reproduce successfully.

Sexual Selection

Evolution of traits because they improve mating success, not necessarily survival (e.g., peacock feathers).

Intrasexual Competition

Competition among members of the same sex for access to mates (e.g., male stags fighting with antlers).

Intersexual Selection

Mate choice based on desirable traits (e.g., peahens preferring colorful peacocks).

Gene Selection Theory

Evolutionary theory proposing that genes are the true units of selection; traits that help genes replicate are favored.

Psychological Adaptations

Evolved mental and behavioral mechanisms that solved ancestral survival or reproduction problems (e.g., fear, jealousy).

Sexual Strategies Theory

Theory suggesting men and women evolved different mating strategies: Men = short-term, quantity-based Women = long-term, stability-based. These vary with context and culture.

Error Management Theory (EMT)

Humans evolved cognitive biases favoring less costly mistakes in uncertain situations (e.g., “better safe than sorry”).

Cost Asymmetries

Situations where one error is more costly than another, shaping adaptive decision biases.

Visual Descent Illusion

People overestimate height when looking down, making them less likely to risk dangerous falls.

Auditory Looming Bias

Sounds approaching are perceived as closer than receding ones, helping avoid threats.

Sexual Overperception Bias

Men are more likely to overinterpret friendly behavior from women as sexual interest—an evolved mating bias.

Adaptation

Inherited trait shaped by natural or sexual selection that increases survival or reproductive success.

Nature vs. Nurture

Debate on whether traits are shaped more by genetic inheritance (nature) or environment (nurture).

Behavioral Genetics

Scientific study of how genes and environment interact to influence behavior.

Adoption Studies

Compare adopted children to biological and adoptive parents to separate genetic and environmental effects.

Twin Studies

Compare identical (MZ) and fraternal (DZ) twins to assess genetic contributions to traits.

Monozygotic Twins

Identical twins who share 100\% of genes.

Dizygotic Twins

Fraternal twins who share 50\% of genes—genetically like regular siblings.

Jim Twins Example

Identical twins raised apart showing striking similarities—used to demonstrate heritability.

Heritability Coefficient (h^2)

Statistic (0-1) estimating how much of a trait’s variation is due to genetic factors.

Phenotypic Plasticity

Ability of one genotype to produce different phenotypes depending on environment.

Genotype

An organism’s complete set of genes.

Phenotype

Observable traits resulting from interaction between genes and environment.

Alleles

Different forms of the same gene.

Homozygous

Two identical alleles for a gene (AA or aa).

Heterozygous

Two different alleles for a gene (Aa).

Locus

Specific location of a gene on a chromosome.

Chromosomes

Structures made of DNA containing genes; humans have 23 pairs.

Single-Gene Trait

Trait determined by one gene (e.g., earlobe attachment).

Polygenic Trait

Trait influenced by multiple genes (e.g., height, intelligence).

ACTN3 Gene

Gene linked to athletic performance; affects muscle fiber type: Full = power Short = endurance.

Epigenetics

Study of changes in gene expression without altering DNA sequence; influenced by environment.

Epigenome

Collection of all chemical modifications to DNA and histones that regulate gene activity.

DNA Methylation

Addition of methyl groups to DNA (often cytosine) that typically silences gene expression.

DNA Methyltransferases (DNMTs)

Enzymes that add methyl groups to DNA, controlling gene silencing.

Histone Acetylation

Addition of acetyl groups to histones that loosens DNA and increases gene expression.

Histone Deacetylation (HDAC)

Removal of acetyl groups from histones, tightening DNA and decreasing gene expression.

Histone Code

Hypothesis that specific combinations of histone modifications regulate gene activity in different cell types.

Chromatin

Complex of DNA and histone proteins forming chromosomes; regulates gene accessibility.

Nucleosome

Basic unit of chromatin—DNA wrapped around a cluster of eight histone proteins.

Epigenetic Variation Over Lifespan

Identical twins become more epigenetically different as they age, leading to behavioral and health differences.

Environmental Influence on Epigenetics

Factors like stress, diet, toxins, or parenting alter methylation/acetylation, changing gene expression.

Maternal Stress Example

High stress in mothers → increased infant DNA methylation → fewer stress hormone receptors → greater stress reactivity.

Rodent Maternal Care Example

Rat pups with nurturing mothers show more stress regulation; neglected pups show higher stress and methylation.

Parental Investment and Offspring Stress

Early-life parental care shapes gene expression affecting stress, emotion, and reproduction.

Histone Code Hypothesis

Proposes specific histone modifications act as a “code” influencing which genes are active in different cells.

Epigenetic Inheritance

Transmission of gene expression patterns (not DNA changes) across generations due to epigenetic marks.

Phenotypic Transmission

Passing down of behavioral or physical traits via epigenetic mechanisms, not direct DNA mutations.

Big Picture of Epigenetics

Shows how environment interacts with genes to shape emotion, cognition, and health—key to psychology.

Modern View of Nature and Nurture

Genes and environment always interact; neither acts alone to produce behavior.

Eugenics (Historical Context)

Discredited movement that attempted to control human traits through selective breeding.

Adaptation Summary

Every evolved physical or psychological trait exists because it solved an ancestral problem of survival or reproduction.