ELI5: Explain Like I'm 5

theory of evolution

The theory of evolution is the idea that all living things have descended from one or a few common ancestors that lived a long time ago. Those ancestors slowly changed over time, passing the changes down to their descendants. Sometimes the changes helped the descendants survive better and have more babies, so the changes were passed down more often. Over many hundreds or thousands of years, this process repeated and eventually resulted in the different plants and animals we see around us today.
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