Quantitative Biology

The Everest Hypothesis: Sexual Complexity as a Test of Replication Fidelity

Authors: Patrick D. Shaw Stewart
Comments: 30 Pages.

Sexual reproduction is nearly universal among complex organisms, yet the reasons for itselaborate accompaniments—from grueling migrations to intricate courtship displays—remainpuzzling. The Everest hypothesis proposes that this reproductive "excess" complexity evolved toexpose subtle defects in replication fidelity to selection. It rests on three key ideas: first, becausenatural selection acts on immediate fitness, it is often blind to mild mutator alleles that slightlydegrade germline DNA replication accuracy. Second, environmental instability exacerbates thisproblem by transiently favoring elevated mutation rates for short-term adaptation, even as theythreaten long-term genomic integrity. Third, complex, multigenic reproductive traits function asdemanding tests that magnify the phenotypic impact of mutational noise, allowing mate choiceor selective fertilization to purge high-mutation lineages. The hypothesis therefore predicts arise-and-fall dynamic in which mutator lineages increase during environmental change but arelater eliminated, and that recombination with residual high-fidelity genotypes can restorefidelity without erasing adaptation. The paper also makes concrete predictions and proposesspecific experiments to test these mechanisms. On this view, the elaborate accompaniments ofsex across the tree of life are not arbitrary ornaments, but evolved instruments of qualitycontrol that help lineages maintain genomic integrity in fluctuating environments.
Category: Quantitative Biology