What is evolution?

Evolution is change in heritable characteristics of populations across generations. It is a central biological framework explaining diversity and relationships among organisms. It differs from changes occurring within one individual’s lifetime. Evolutionary processes involve inherited variation interacting with reproduction and environmental conditions.

Main evolutionary mechanisms

1. Genetic variation Mutations can introduce DNA sequence changes. Recombination during sexual reproduction rearranges existing variants into new combinations. Their effects depend on context; not every mutation is beneficial or harmful. Mutations are not assumed to arise in order to satisfy a need. 2. Natural selection When inherited traits influence reproductive success in a particular environment, their frequencies can change across generations. Fitness is not simply physical strength: it concerns context-dependent contributions to survival and reproduction. Changing environments can change which traits are advantageous. 3. Drift and gene flow Genetic drift changes variant frequencies by chance and can be especially influential in small populations. Gene flow transfers genetic material between populations. Evolution is not natural selection alone; these mechanisms can operate together.

Evidence, speciation and misconceptions

4. Common ancestry and evidence Fossils, comparative anatomy, biogeography and DNA comparisons investigate biological history. Agreement between independent evidence matters. Similar appearances do not always mean close ancestry; similar environments can independently favor similar adaptations. 5. Speciation Differences can accumulate when reproductive connections between populations diminish. Geographic separation can contribute but is not the only route. Species concepts do not apply equally easily to every group; asexual organisms and fossils may require different approaches. 6. Common misunderstandings Evolution has no predetermined goal of perfection. Humans did not descend from monkey species living today; they share past common ancestors with them. Evolutionary biology studies changes in life, while research into life’s first origin addresses a related but distinct question.