The Maximum Genetic Diversity Theory: A Comprehensive Framework for Understanding Evolutionary Processes

A good understanding of evolutionary processes is essential for addressing a variety of important scientific questions. In the early 1960s, the discovery of protein sequences revealed an unexpected phenomenon known as genetic equidistance, which led to the development of the molecular clock hypothesis. This hypothesis later inspired Kimura's neutral theory (NT). While the NT has served as a useful null model, it has struggled to fully explain genetic diversity. Systematic neutrality tests of the human mitochondrial genome have raised questions about the validity of the NT. As the molecular clock has fallen out of favor, this has also affected the standing of the NT and reintroduced the genetic equidistance phenomenon (GEP) as an unresolved issue. In the early 2000s, renewed interest in this phenomenon led to the formulation of the maximum genetic diversity (MGD) hypothesis, which offers a more comprehensive approach to understanding evolution. Analytical tests suggest that current genetic distances are primarily at maximum saturation rather than steadily increasing, as previously proposed by the molecular clock and NT. The MGD theory posits that macroevolution – from simple to complex organisms – involves a punctuated rise in epigenetic complexity accompanied by a decrease in the maximum genetic diversity a taxon can sustain. This theory has undergone extensive testing, contributing to our evolving understanding of evolutionary processes.