ABSTRACT
So far we have taken the growth rates of a population (both l, the growth rate of the working population, and lp , the growth rate of the property-owning population) as a constant unaffected by economic changes, but in this and the following chapter we shall turn our attention to the possibility that changes in the standard of living may themselves affect the growth rate of a population. A change in the standard of living might affect the growth rate of a population either through its effect upon mortality or through its effect upon fertility or through both influences. Suppose that a low standard of living led to malnutrition and that this caused (i) a higher incidence of disease and death and (ii) a lower biological fecundity among women. Then a fall in the standard of living would tend to raise death rates and lower birth rates and this in turn would tend to lower the rate of growth of population.
