Since there is no survival value in an animal' s having an organ that is able to function when all its other organs have broken down to such a degree that the animal dies, it is a result of the efficiency of natural selection that no organ is likely to evolve in such a way that it greatly outlasts the body' s other organs
A store in a lower-income neighborhood finds that it is unable to sell its higher-priced goods and so stocks them only when ordered by a customer.