Life Extension and Overpopulation: Demography, Morals, and the Malthusian Objection

Abstract

One of the main objections to life extension is that life extension will cause severe overpopulation. This objection presents both moral and demographic issues. To explore the demographic issue, we present an updated and improved version of the formula in chapter six of New Methuselahs for projecting the demographic impact of life extension. The new version includes additional demographical factors such as non-aging related causes of death. According to projections generated with this revised formula, moderate life extension (a life expectancy of 120 years) will not significantly increase population at the fertility rates current in the developed world, but radical life expectancy (halting aging completely, leading to an average life expectancy of 1000 years) can lead to severe overpopulation even at very low fertility rates. This formula also enables us to ascertain what fertility rate and birth spacing will prevent life extension from causing severe overpopulation. The moral issues arise if radical life extension causes overpopulation severe enough to outweigh the benefits it brings. New Methuselahs proposed a reproductive policy for avoiding severe overpopulation by limiting reproduction for those who use life extension. We then consider a moral objection to this policy that was not discussed in New Methuselahs: it is not likely that society will succeed in imposing limits to reproduction, therefore, it is likely that radical life extension is morally wrong. We respond to this objection and defend our response against two further objections.

Appendices

Appendix I: Details on the formula used for the projections

$${\text{P}}_{{\text{t}}} = {\text{P}}_{{{\text{t}} - {1}}} + \mathop \sum \limits_{{{\text{g}} = 1}}^{{\text{n}}} \left( {({\text{P}}_{{{\text{g}} - 1}} \times \left( {1 - {\Omega }} \right)^{ny} ){\Phi }_{{\text{g}}} {\upbeta }_{{\text{g}}} } \right)_{{\text{t}}} - \mathop \sum \limits_{{{\text{g}} = 1}}^{{\text{n}}} ({\uptheta }_{{\text{g}}} )_{{\text{t}}}$$

The above-mentioned collection of variables can be interpreted as follows:

P_t is the total population at time t. P_t-1 is the initial population one time prior to the time t. Φg demonstrates the gender ratio for generation g while βg represents the number of children per woman in generation g. θg represents the number of age-related causes of death for generation g. Ω shows the annual rate for nonage-related causes of death which includes accidents, disease, war, crime, terrorism, suicide, and homicide. y is the number of years that forms each generation while n is for calculating the frequency of the death rate (e.g., if the rate is annual n will 1, if the rate is biannual, n will be 2, and if the rate is monthly, n will be 12). Finally, we used Σ to calculate for all generations during the span of time we considering. Therefore, Σ represents the sum of the multiplication of the three variables in the parentheses for each generation of women having children at that time (which are between 1 and n (1, n)) must be added to the sum for every other generation of women having children at that time.

Appendix II:Tables Used to Generate Figs. 1, 2, 3 and 4

See Tables 1, 2, 3 and 4

Table 1 Life expectancy of 1000 with 1.8 children per woman at age 20 (Corresponding data for Fig. 1)

Table 2 Life extension of 1000 years and total fertility rate .5 child per woman at age 20 (Corresponding data for Fig. 2)

Table 3 Life extension of 1000 years and total fertility rate 1 child per woman at age 20, 40, 800, and 900 (Corresponding data for Fig. 3)

Table 4 Life extension of 1000 years and total fertility rate 1 child per woman at age 500, 540, 800, and 900 (corresponding data for Fig. 4)