Survival of the Survivors
Most peoople think that, “fitness” meaning “suitability for a purpose,” survival of the fittest means that the smarter, stronger, and faster survive and reproduce. It does not. The study of such things is called population genetics and, as a professor of it says, “In population genetics, fitness means the rate of successful reproduction, nothing else.” That is, fitness does not promote survival, but is inferred from it. The circularity is well known: Why do they survive? Because they are fit. How do you know that they are fit? Because they survive.
via Fred On Everything.