"物竞天择 适者生存"who can help me translate this sentence?

问题描述:

"物竞天择 适者生存"who can help me translate this sentence?

Only the fittest survive

This is Darwin's theory of evolution, said is the world's species competition, only the strong can survive.
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物竞天择:natural selection
适者生存:
1.survival of the fittest
2.the survival of the fittest

Natural selection assures the survival of the fittest.