Evolutionary orthodoxy: how and why the evolutionary theory of aging went astray.

Prevailing ideas of how aging evolved are a poor fit with the picture of aging that is developing from genetics labs and breeding experiments. Nevertheless, the community of theorists is reluctant to consider alternate approaches because the differences are profound, calling into question much of the standard methodology of Population Genetics. (At stake is not the legacy of Darwin, but the particular model of Darwinian selection that has dominated the field of research since the middle of the 20th Century). This model may be a historic artifact, arising from a time before computers, when a premium was placed on equations that could be solved analytically. The standard Population Genetic model gained credibility through agreement with laboratory experiments that were designed to realize the assumptions of the model, rather than to mirror conditions in the natural world. Models of evolution based on pure individual selection or inclusive fitness cannot explain the basic phenomenology of aging. Aging is not the only area of conflict, however. Other areas which present difficulties for the standard model include the origin of sex, the maintenance of diversity, the basis of evolvability (including hierarchical structure of the genome), occasional persistence of eusociality without close relatedness, and many examples of strong altruism. From many corners of the field, creative and visionary biologists are calling for a re-thinking of the fundamental mechanisms of natural selection.