 Numerous evolutionary questions can be addressed using simple population-genetic models of this sort. For example, by incorporating a parameter which measures the fitness differences between genotypes, we can study the rate of evolutionary change, permitting us to ask questions such as: how long will it take for selection to increase the frequency of the \(A_1\) allele from 0.1 to 0.9? If a given deleterious allele is recessive, how much longer will it take to eliminate it from the population than if it were dominant? In this way, population genetics converted the theory of evolution into a quantitatively precise one.