Choice bio

Biological Basis of Choice

Human decision-making is deeply rooted in biology, meaning our brain, genes, and evolution shape what we prefer and choose.

Animals as Models

Scientists study animals to understand human behavior because we share evolutionary history and brain systems with them.

Striatum

A brain region involved in reward and value-based decision-making, especially learning what is 'worth it.'

Amygdala

A brain region that processes fear, threats, and negative emotions, guiding avoidance decisions.

Insula

A brain region tied to pain, disgust, and internal bodily states like hunger or thirst.

Hormones

Chemical messengers that influence behavior more slowly than neurons by changing how we weigh decisions.

Cortisol

A stress hormone that increases vigilance and risk avoidance while reducing exploration.

Testosterone

A hormone linked to competition, status-seeking, and risk-taking behavior.

Oxytocin

A hormone associated with bonding, trust, and social connection.

Fast vs Slow Threat Processing

The brain has a fast pathway (thalamus → amygdala) and a slow pathway (via cortex) for responding to danger.

Learned Preferences

Many of our likes and dislikes come from learning through rewards (striatum) and punishments (amygdala).

Natural Selection

Traits that improve survival and reproduction become more common over generations.

Gene

A unit of heredity that carries biological information affecting traits and behavior.

Phenotype

Observable traits resulting from genes interacting with the environment.

Fitness (Evolutionary)

The likelihood of passing on your genes to the next generation.

Evolutionary Psychology

The idea that many mental processes evolved to solve survival problems.

Modules (Evolutionary)

Specialized mental systems designed for specific tasks like food, mating, or social interaction.

Food Preferences (Evolutionary)

Humans naturally prefer sweet and fatty foods and avoid bitter ones because of survival value.

Neophobia

Fear of new foods, especially in children, to avoid potential toxins.

Mating Preferences

Differences in male and female preferences shaped by evolutionary pressures.

Kin Selection

Preference for helping relatives because they share your genes.

Inclusive Fitness

The idea that helping relatives increases your overall genetic success.

Human vs Animal Cognition

Humans have a more developed prefrontal cortex, allowing reasoning, planning, and self-control.

Cultural Override

Humans can reshape biological instincts through culture and learning.

Evolutionary Mismatch

Traits that were once adaptive can become harmful in modern environments.

Supernormal Stimuli

Exaggerated versions of natural stimuli that trigger stronger-than-normal responses.

Gwynne & Rentz Beetle Study

Male beetles preferred mating with beer bottles over females because the bottles exaggerated mating cues.

Jaffe et al. Moth Study

Male moths were more attracted to synthetic pheromones than real females.

Foraging

The process of searching for and exploiting resources like food.

Marginal Value Theorem (MVT)

A model stating you should leave a resource when its reward rate drops below the average elsewhere.

Patch-Leaving Decision

The choice between staying in a current resource or switching to another.

Threshold Heuristic

A simple rule where you switch options once value falls below a certain level.

Anterior Cingulate Cortex (ACC)

A brain region that tracks reward rates and helps decide when to switch tasks.

Behavioral Genetics

The study of how genes influence behavior and individual differences.

Twin Studies

Research comparing identical and fraternal twins to estimate genetic influence.

Turkheimer's First Law

All human behavioral traits are partly heritable.

Turkheimer's Second Law

Shared environment has less influence than genes on many traits.

Turkheimer's Third Law

Not all variation is explained by genes or family; randomness matters.

Fourth Law of Behavioral Genetics

Traits are influenced by many genes, each with tiny effects.

Genome

The full set of genetic material in a person.

SNPs (Single Nucleotide Polymorphisms)

Small genetic variations used to study traits.

Genome-Wide Association Studies (GWAS)

Large studies scanning the genome to find genetic links to traits.

Polygenic Risk Scores (PRS)

Scores that combine many genetic variants to predict traits.

Daviet & Nave Taste Study

Found genetic data can help predict food preferences beyond demographics.

Candidate Gene Studies

Early studies linking single genes to traits, often unreliable.

Direct-to-Consumer Genetic Testing

Services like 23andMe that provide genetic data to individuals.

Ethical Issues in Genetics

Genetic data is sensitive, hard to anonymize, and affects relatives.

Lewontin (1972)

Found most genetic variation exists within races, not between them.

Race and Genetics Misuse

Genetic research has been misused to justify inequality, but evidence shows environment plays a major role.

Risky Behavior GWAS (Linnér et al., 2019)

Identified genetic links to risk-taking behaviors like smoking and speeding.

Gene-Brain-Behavior Pathway

Genes influence brain structure, which influences behavior.