The life-dinner principle (unequal selection pressures) ¶ ‘The rabbit runs faster than the fox, because the rabbit is running for his life while the fox is only running for his dinner’ (Dawkins 1979, after Aesop). There is a built in imbalance between predator and prey with respect to the penalty of failure. Mutations that make foxes lose races against rabbits might therefore survive in the fox gene pool longer than mutations that cause rabbits to lose races can expect to survive in the rabbit gene pool.