SURVIVAL OF THE FITTEST

n. phr. The staying alive or in action of the best prepared; often: idea that those living things best able to adjust to life survive and those unable to adjust die out. Life in the old West was often a case of survival of the fittest. With changes in the world's climate, dinosaurs died but many smaller animals lived on. It was survival of the fittest. On the 50-mile hike it was survival of the fittest; only 12 out of 25 Scouts finished.