Directionality Theory and Mortality Patterns Across the Primate Lineage

Empirical studies of aging in primates show that local selective forces rather than phylogenetic history determine the exceptional nature of human longevity (Bronikowski, et al., 2011). This article proposes an evolutionary rationale for this pattern of primate mortality by invoking the parameter, Life-Table Entropy, a measure of the uncertainty in the life span of a randomly chosen newborn. Life-table entropy is positively correlated with maximal life span, that is, the mean life span of a species living under favourable conditions. The logic which underlies the exceptional nature of human longevity derives from the terrestrial life-history of humans - a singularity within the primate lineage; and the concomitant ecological constraints - the hunter-gatherer, agricultural, and industrial modes of subsistence, that have defined human evolutionary history. The effect of these ecological constraints on the evolution of life span is encoded in the Entropic Principle of Longevity: life-table entropy increases in equilibrium species, populations evolving in environments with stable, renewable resources; and decreases in opportunistic species, populations subject to fluctuating resource endowments. The Entropic Principle of Longevity is a derivative of Directionality Theory, an analytic study of the evolutionary process of variation and selection based on Evolutionary Entropy, a statistical measure of the uncertainty in the age of the mother of a randomly chosen newborn. Evolutionary entropy is the organizing concept of The Entropic Principle of Evolution: Evolutionary Entropy increases in equilibrium species and decreases in opportunistic species.