OPTIMALITY THEORY, GOMPERTZ' LAW, AND THE DISPOSABLE SOMA THEORY OF SENESCENCE

Area of Science:

• Evolutionary biology
• Gerontology
• Mathematical modeling

Background:

• Senescence, or aging, is a complex biological process.
• The disposable soma theory posits aging results from resource allocation trade-offs between reproduction and somatic maintenance.
• Existing evolutionary theories of aging have not fully explained observed mortality patterns.

Purpose of the Study:

• To investigate the evolutionary basis of senescence using dynamic programming models.
• To determine the optimal relationship between reproduction, somatic repair, and mortality.
• To predict the shape of mortality-rate-versus-age curves based on the disposable soma theory.

Main Methods:

• Construction and analysis of dynamic programming models.
• Modeling the trade-off between resource allocation for reproduction and somatic repair.
• Examining the relationship between this trade-off and age-dependent mortality patterns.

Main Results:

• Models predict mortality rates that increase at an accelerating rate with age, potentially approaching a linear rate at high mortality.
• The disposable soma theory offers a framework consistent with various mortality curve shapes, not exclusively Gompertz' Law.
• An exponential increase in death rate with age (Gompertz' Law) is shown to be only one possibility among many under this theory.

Conclusions:

• The disposable soma theory provides a robust evolutionary explanation for senescence.
• Observed mortality patterns, including exceptions to Gompertz' Law, are consistent with resource allocation trade-offs.
• The theory suggests that universal laws of aging may not apply due to variations in the repair-reproduction trade-off.