Why does evolution have to with change over time?

Evolution is the change in an animal over time. Evolution causes this one animal to branch out into many different species of animals.
How evolution starts- There is a mutation in the genes of one animal. If the mutation helps the animal, than the animal breeds and passes on this mutation. This is natural selection. Natural selection is the starting point of evolution because all of the helpful mutations get passed down to change the species over time for the animals' benefit.
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