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What is natural selection?

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Quick answer

Natural selection is the process where organisms with traits better suited to their environment tend to survive and reproduce more, passing those traits on. Over many generations this gradually shapes species — the core mechanism of evolution that Charles Darwin described.

Key things to understand

  1. Individuals in a population vary, and some of those variations are inherited.
  2. Those with traits that help them survive and reproduce leave more offspring.
  3. Helpful traits become more common over generations; unhelpful ones fade.
  4. Given enough time, this can produce entirely new adaptations and even new species.
  5. It is not random: the environment 'selects' which traits succeed, though the variations themselves arise randomly.

People also ask

Is natural selection the same as evolution?
Natural selection is the main mechanism that drives evolution; evolution is the broader change in species over time that results from it and other processes.
Is 'survival of the fittest' accurate?
Roughly — but 'fittest' means best suited to reproduce in a given environment, not strongest or fastest. Which traits are fit depends entirely on the surroundings.
Does natural selection have a goal?
No. It has no foresight or purpose; it simply favors whatever traits happen to aid survival and reproduction in the current environment.