Evolution is cumulative change in heritable characteristics of populations, driven by variation, inheritance, selection, and changing allele frequencies across generations.
Coverage 2011–2024 · Updated 15 Jul 2026
Evolution is a change in heritable characteristics of populations across generations.
Mutation and recombination create variation, while selection, drift and gene flow change allele frequencies. Individuals do not evolve because a population-level frequency changes over time. This population-level definition is essential when separating evolution from an individual’s lifetime acclimation.
Trace the population process:
If a drought-resistant allele becomes more common after repeated dry years, the population has evolved; one plant becoming drought-resistant during its life has not.
Evolution is not progress toward perfection; it is change relative to a particular environment.
This objective is assessed through essay response, commonly using Define / Explain / Outline.
Define / Explain / Outline
Build the answer around this relationship: Evolution is cumulative change in heritable characteristics of a population across generations.
Treating evolution as a change acquired by an individual during its lifetime rather than a heritable population change.
Representative question
Explain how the process of evolution occurs.
The core A4.1 answer moves from evidence to mechanism. Define evolution as heritable population change across generations. Use molecular universals and sequence differences, selective breeding, homology, and convergence as evidence for common ancestry and divergence. Then explain speciation as reduced gene flow followed by divergence of isolated gene pools through selection, mutation, and drift.
