How does natural selection work?
Darwin identified four conditions: individuals in a species vary; some of that variation is heritable; more offspring are born than can survive; and individuals with advantageous traits survive and reproduce more. Repeat that over many generations and the population's traits shift.
What are real examples, and common myths?
During a drought on the Galápagos, only hard seeds were left, so finches with bigger beaks survived and the next generation's average beak size grew. In industrial Britain, dark peppered moths camouflaged on sooty trees became common. Today, overusing antibiotics selects for resistant bacteria. "Survival of the fittest" doesn't mean the strongest—it means the most reproductively successful in a given environment—and evolution has no built-in goal.
FAQ
- Are natural selection and evolution the same?
- Natural selection is one major mechanism of evolution; genetic drift, mutation, and gene flow also drive it.
- What's artificial selection?
- Humans choosing which traits to breed for, as in dog breeds.
Sources reviewed: 2026-10-25
References
- Darwin, C. (1859). On the Origin of Species. John Murray.
- Grant, P. R., & Grant, B. R. (2006). Evolution of character displacement in Darwin's finches. Science, 313(5784), 224–226.
- Cook, L. M., et al. (2012). Selective bird predation on the peppered moth. Biology Letters, 8(4), 609–612.