(0) 🧬 CHAPTER 3: THE EVOLVING MIND FLASHCARDS

What does the term nature vs. nurture refer to?

The debate over whether behavior and traits are shaped more by genetics (nature) or environment and experience (nurture).

Who coined the phrase "nature vs. nurture"?

Francis Galton.

How are nature and nurture related?

They are intertwined—genes and environment interact to shape both physical and behavioral traits.

What is a gene?

A small segment of DNA on a chromosome that codes for a specific protein.

What is a genotype?

An individual's complete set of genetic material (alleles).

What is a phenotype?

The observable traits or behaviors that result from genetic and environmental interaction.

What is genetic expression?

The process by which genetic instructions are turned into physical or behavioral traits.

What is an allele?

One of several alternative forms of a gene that can occupy a specific position on a chromosome.

Define homozygous and heterozygous.

Homozygous = two identical alleles for a trait; Heterozygous = two different alleles for a trait.

What is a dominant allele?

An allele that determines a phenotype whether it appears in one or both copies.

What is a recessive allele?

An allele that only produces its phenotype when two copies are present.

What is relatedness?

The probability that two people share the same allele from a common ancestor.

What does genetic relatedness explain?

Why we show altruism and kin selection—helping relatives increases survival of shared genes.

How many chromosome pairs do humans have?

23 pairs (46 total).

Which pair determines biological sex?

The 23rd pair — the sex chromosomes: XX in females, XY in males.

Why do some traits differ by sex?

Because the X and Y chromosomes carry different genes; recessive traits on the X can affect males more (e.g., color blindness).

What is behavioral genetics?

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

What is heritability?

A statistic (ranging from 0 to 1) estimating how much of the variation in a trait is due to genetic factors.

How are heritability estimates determined?

Through twin and adoption studies comparing identical (monozygotic) and fraternal (dizygotic) twins.

What does a heritability score of 0 mean?

Genes play no role in the variation of that trait.

What does a heritability score of 1.0 mean?

All variation in the trait is due to genetics.

What is the typical range of heritability for most human traits?

Between 0.30 and 0.60.

What are concordance rates?

The likelihood that one individual has a trait if another related person has it.

What is a candidate gene?

A specific gene believed to influence a particular trait more than others.

What is epigenetics?

The study of how the environment affects gene expression—turning genes on or off without changing the DNA sequence.

What is a genome-wide association study (GWAS)?

A large-scale scan of DNA from many individuals to identify genetic variations linked to specific traits.

What environmental factors can cause epigenetic changes?

Nutrition, stress, toxins, disease, and drugs.

What does epigenetics tell us about nature vs. nurture?

Genes provide the potential, but environment determines how and when that potential is expressed.

Define evolution.

Descent with modification from common ancestors over generations.

What is natural selection?

The process where traits that improve survival or reproduction become more common in future generations.

What is a mutation?

A random error in DNA replication that introduces new genetic variation.

What is migration (in evolutionary terms)?

The movement of individuals or genes to new populations, introducing genetic diversity.

What is genetic drift?

Random changes in gene frequencies, especially in small populations, due to chance events.

What is fitness?

The ability of an organism's genotype to reproduce successfully relative to others.

What is adaptation?

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

What are hominins?

Bipedal species that are ancestral to humans.

Who was Homo erectus?

An early human ancestor living about 1.5 million years ago.

What distinguishes humans (Homo sapiens) from other species?

The complexity of our social behavior and cognitive abilities.

Why hasn't the human brain continued to grow larger?

Large brains are energy-expensive (20% of body resources) and limited by the size of the birth canal.

Has human brain evolution stopped?

No — brain size has stabilized, but intelligence and cognitive function continue to evolve.

What is altruism?

Helping another individual at a personal cost or with no direct benefit.

What is reciprocal altruism?

Helping others with the expectation that they will help you later.

How does altruism relate to evolution?

It promotes survival of genes shared with others and strengthens group cooperation.

What is sexual selection?

The evolutionary process where traits that aid in attracting or competing for mates become more common.

What is intrasexual selection?

Competition within one sex (usually males) for access to mates (e.g., fighting, displays of dominance).

What is intersexual selection?

Traits that attract the opposite sex (e.g., humor, intelligence, beauty).

What is parental investment?

The time, effort, and resources each parent contributes to raising offspring, influencing mate preferences.

What is culture?

Shared beliefs, practices, customs, and knowledge passed from one generation to another.

How does culture influence evolution?

It shapes behaviors and mating patterns that can affect which genes are passed on.

What's an example of genetic spread through culture?

Genghis Khan's Y chromosome appears in about 16 million living men today.

How do genes and environment interact?

Genes set potentials and limits, while environment and culture determine how those potentials are expressed.

What does the phrase "nature via nurture" mean?

Genetic potentials are realized through environmental experiences and learning.