The Evolutionary Costs of Institutional Design: A Mathematical and Empirical Analysis of Strict Lifetime Monogamy

Sexual selection operates as a natural mechanism of genome purification, resting upon one essential structural precondition: measurable variance in individual reproductive success. Should such variance be erased, whether through ecological constraint, experimental manipulation, or formal social institution, two core evolutionary processes begin to falter: the selective purging of mildly deleterious mutations slows or ceases entirely, and the gradual proliferation of advantageous genetic variants is held in check. Over time, collective population resilience amid environmental fluctuation will inevitably diminish. These outcomes are not speculative inference, but necessary deductions derived from established population genetics, including Fisher’s fundamental theorem and the standard mutation–selection balance framework. Controlled multi-generational studies employing \textit{Tribolium castaneum} and \textit{Rhizoglyphus robini} offer direct empirical corroboration. Under experimentally enforced lifelong monogamy sustained across dozens of generations, constrained populations underwent steady fitness decline and faced complete collapse when exposed to environmental stress, while polygamous control lineages remained viable. Genomic assessment further confirms that functional sexual selection effectively moderates harmful mutation load without dissipating stable standing genetic diversity. This paper assembles four complementary lines of biological observation—molecular, physiological, epidemiological, and demographic—to illustrate the irreversible nature of cumulative mutation accumulation, the latent biological fragility obscured by contemporary medical intervention, and the analytical error inherent to simplistic cross-population comparison. Though socially functional in many respects, strict lifetime monogamy carries a quantifiable, escalating, and intergenerationally unagreed evolutionary burden.

The Evolutionary Costs of Institutional Design I