Selectively Advantageous Instability and Information Theory in Sex-specific Aging

Biological information is typically selected to maintain its fidelity. Nevertheless, accurate preservation frequently occurs alongside regulated processes that induce state changes. Selectively advantageous instability (SAI) is explored in this context as instability that is selected for because it enables access to beneficial alternatives.

Within a simple AB replicator model, the degradation of B results in the breakdown of a functional AB complex, but also releases A, which allows the formation of the superior AAB replicator. Therefore, positive selected instability broadens the range of occupied states and consequently raises Shannon state entropy compared to a system that is perfectly stable.

Modeling indicates that active destabilization is selected when environmental changes, passive errors, destabilization costs, and the relative importance of active versus passive variation exceed a certain threshold. Crucially, when actively generated variation is sufficiently organized, selection concurrently promotes enhanced maintenance and intensified active destabilization of the same information channel.

This relationship is termed stabilization-destabilization complementarity. Shannon entropy measures uncertainty, while relative entropy gauges the discrepancy between the generated and fitness-relevant state distributions. Aging is not solely a result of reversible exploration. Instead, it arises when selected exploration leads to ongoing or cumulative loss of maintained organization.

Age and sex extensions demonstrate how delayed costs and shared genetic control can create antagonistic pleiotropy and sexual conflict. Empirical tests are provided using published phenotype switching and environmental memory data. A unified interpretation is proposed, in which SAI can be selected as a means of adaptive state space exploration even when long-term information displacement is costly.