Effects of mortality decline on aging

Table 7.5 from Preston S, Heuveline P, Guillot M Demography. Measuring and Modeling Population Processes
Effects of mortality decline on intrinsic growth and age structure
Change in LEX	Corresponding absolute change in:
	Intrinsic growth rate	Mean age of the population	The proportion aged 0 to 14 years	Proportion aged 65+
40 >> 50	0.0068	-0.83	0.0198	-0.0001
50 >> 60	0.0054	-0.71	0.0162	-0.0012
60 >>70	0.0040	-0.34	0.0103	0.0014
70 >> 80	0.0021	0.60	-0.0010	0.0120
Data source: Coale and Demeny (1983) West, model female life table, combined with GRR of 2

...mortality declines have, throughout human history, tend to make tend to make populations younger. Once a population reaches a life expectancy of approximately 65 years, subsequent mortality declines tend to produce an older population. Because they typically induce a mild decline in the proportion of the population of childbearing ages, mortality declines here exerted a slight depressing effect on the crude birth rate. Table 7.5 shows the effect of mortality decline on the intrinsic growth rate and the intrinsic age structure of a theoretical population with a GRR of 2 and a model age pattern of mortality. For more details see Coale A., 1972, The growth and structure of human populations or Preston S., 1974, Effect of mortality change on stable population parameters