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What is evolution?

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Quick answer

Evolution is the process by which living things change across generations as heritable traits become more or less common. Driven mainly by natural selection, it explains the diversity of life and how species adapt to their environments. Individuals vary, and some variations are inherited by offspring.

Key things to understand

  1. Individuals vary, and some variations are inherited by offspring.
  2. Traits that aid survival and reproduction become more common over generations (natural selection).
  3. Over long timescales, small changes accumulate into new species.
  4. Evidence comes from fossils, DNA, and observed change in living populations.

People also ask

What is natural selection?
The process where organisms better suited to their environment tend to survive and reproduce more, passing on their helpful traits.
Is evolution 'just a theory'?
In science a theory is a well-tested explanation backed by extensive evidence — evolution is among the best-supported.
How long does evolution take?
It can be fast in microbes (observable in years) but usually unfolds over thousands to millions of years for larger organisms.

Part of the guide: Nature & Earth: Living Things and Rocks →