Biology: Genetics, Evolution, and Human Variation Key Concepts

Punnett squares

The possible combinations of parental alleles and the probability of offspring genotypes.

Genetic Fitness

An individual's ability to survive and reproduce, passing on genes to the next generation.

Galápagos Drought

Only birds with bigger, stronger beaks could crack tough seeds and survive.

Melanin

The pigment in skin, hair, and eyes that gives color and protects against UV radiation.

Phenotype

The physical expression of a trait (eye color, height, skin tone).

Subfields of Anthropology

Biological (physical), Cultural, Linguistic, Archaeology.

Lamarck's belief

Traits acquired during life (like muscles) could be inherited — wrong idea.

Lyell's contribution

Uniformitarianism (earth shaped slowly over time).

Malthus's contribution

Populations grow faster than food → struggle for existence.

Darwin's addition

Natural selection as the mechanism of evolution.

DNA

A molecule with instructions for building proteins.

DNA bases

A, T, G, C.

Central Dogma

DNA → RNA → Protein → Trait.

Natural Selection

Variation, heritability, and differential survival/reproduction.

Genotype

The genetic makeup (alleles you have).

Forces of Evolution

Mutation, Gene Flow, Genetic Drift, Natural Selection.

Mutation

Random DNA change creating new variation.

Gene Flow

Movement of alleles between populations.

Genetic Drift

Random change in allele frequency, especially in small populations.

Species (biological definition)

A group that can breed and produce fertile offspring.

Allopatric speciation

New species form after populations are split by a barrier.

Sympatric speciation

New species form in the same place (often due to niche use).

Cladistics

A method of classifying species based on shared evolutionary traits.

Cladogram

A branching 'family tree' of evolutionary relationships.

Acclimatization

Short-term, reversible adjustment (like tanning or breathing faster at high altitude).

Adaptation

Long-term genetic change passed down (like Bajau larger spleens for diving).

Human variation

Traits like skin color shift gradually with geography, not in discrete 'races.'