Thinker
Before Darwin
Organic evolution theories sit in Paper 1 biological anthropology — do not mix them up with Tylor’s cultural ladder.
- Creationism / catastrophism: species as made, then reset by disaster — not a research programme.
- Lamarck: new needs, use and disuse, inheritance of acquired characters, a drive toward complexity.
- Giraffe neck is the classroom cartoon; the exam point is acquired-character inheritance — later rejected for the germ line.
Thinker
Darwin and Wallace
- On the Origin of Species (1859): variation, geometric increase (Malthus), struggle, natural selection, descent with modification.
- Darwin lacked a correct heredity theory — that hole is why genetics had to be fused later.
Key points
Weismann, neo-Darwinism, synthetic theory
- August Weismann (1883): germplasm vs soma — acquired body change does not rewrite gametes.
- Neo-Darwinism / modern synthesis: mutation, recombination, drift, flow, inbreeding as sources of variation; selection as the main directional filter; isolation as speciation’s lock.
- Prezygotic isolation (behaviour, gametes) vs postzygotic (sterile or unfit hybrids).
- J.B.S. Haldane’s dilemma: substituting alleles has a ‘cost’ in selective deaths; evolution is not free.
Lamarck
- Use/disuse
- Acquired characters inherited
- Inner drive to complexity
Synthetic Darwinism
- Variation from genes
- Selection on phenotypes
- Speciation via isolation
Key points
Related evolutionary ideas
- Irreversibility (Dollo-type teaching): complex lost structures rarely return exactly — whales and land locomotion.
- Competitive exclusion vs partitioning, mutualism, niche split in nature.
- Adaptive radiation: one lineage, many niches.
- Convergence: similar traits, different ancestry (hummingbird and humming moth).
WRAP Exams coaching notes for UPSC Anthropology optional. Pair with the official syllabus when you need every heading in order.