Значение идиомы survival of the fittest

[survival of the fittest] {n. phr.} The staying alive or in actionof the best prepared; often: idea that those living things best ableto adjust to life survive and those unable to adjust die out.

Lifein the old West was often a case of survival of the fittest.

Withchanges in the world’s climate, dinosaurs died but many smalleranimals lived on. It was survival of the fittest.

On the 50-milehike it was survival of the fittest; only 12 out of 25 Scoutsfinished.