Theory and associated phenomenology for intrinsic mortality arising from natural selection

TL;DR

This paper presents a spatial evolutionary model demonstrating that natural selection can favor intrinsic mortality and programmed death, challenging traditional assumptions and explaining various empirical observations.

Contribution

It introduces a spatial model showing that self-limited lifespan can be evolutionarily advantageous, providing a new theoretical basis for intrinsic mortality.

Findings

Self-limited lifespan benefits lineages over the long term

Shorter lifespan can be favored due to environmental feedback

Empirical data on lifespan and mortality align with model predictions

Abstract

Standard evolutionary theories of aging and mortality, implicitly based on assumptions of spatial averaging, hold that natural selection cannot favor shorter lifespan without direct compensating benefit to individual reproductive success. Here we show that both theory and phenomenology are consistent with programmed death. Spatial evolutionary models show that self-limited lifespan robustly results in long-term benefit to a lineage; longer-lived variants may have a reproductive advantage for many generations, but shorter lifespan ultimately confers long-term reproductive advantage through environmental feedback acting on much longer time scales. Numerous model variations produce the same qualitative result, demonstrating insensitivity to detailed assumptions; the key conditions under which self-limited lifespan is favored are spatial extent and locally exhaustible resources. Numerous empirical observations can parsimoniously be explained in terms of long-term selective advantage for intrinsic mortality. Classically anomalous empirical data on natural lifespans and intrinsic mortality, including observations of longer lifespan associated with increased predation, and evidence of programmed death in both unicellular and multicellular organisms, are consistent with specific model predictions. The generic nature of the spatial model conditions under which intrinsic mortality is favored suggests a firm theoretical basis for the idea that evolution can quite generally select for shorter lifespan directly.