Population control requires that the birth rate equal to the death rate. If it is too low population will decline; if it is too high, population will increase. If either condition persists long enough the population will diminish towards zero or increase towards infinity. Fortunately, the birth trajectory does not have to be set once and for all, but can be adjusted within limits. Since birth and death rates determine whether we are heading for population extinction or explosion, they are well designated "vital statistics." Their understanding and use are a central theme of demographic...