Key points
Mutation
Without mutation, selection and drift have nothing new to work on.
- Mutation: heritable change in DNA — the ultimate source of new alleles.
- Mutagens: physical (UV, X-rays), chemical (base analogues, pollutants), biological (some viruses).
- Most mutations are neutral or harmful; a few are favoured. Anthropology cares because mutation feeds variation.
Concept
Polymorphism
- Genetic polymorphism: two or more alleles at appreciable frequency in a population.
- Balanced (stable) polymorphism: heterozygote advantage — sickle-cell trait and malaria is the set-piece.
- Transient polymorphism: one allele replacing another (industrial melanism as the animal teaching case).
- Use: migration history, disease risk, forensic distinction — not ‘purity’ of groups.
Thinker
Hardy–Weinberg (1908)
- G.H. Hardy and Wilhelm Weinberg: allele and genotype frequencies stay put if assumptions hold.
- Assumptions: large population, random mating, no mutation, no selection, no migration (gene flow).
- p + q = 1; p² + 2pq + q² = 1 for two alleles.
- Human populations almost never meet the ideal — the law is a baseline to measure evolutionary change against.
WRAP Exams coaching notes for UPSC Anthropology optional. Pair with the official syllabus when you need every heading in order.