The Escalation Hypothesis: One Long Argument

Abstract

Ever since Darwin, we have asked: Do predictable rules govern the evolutionary process? The question has attracted the attention of countless evolutionary biologists, paleontologists, and philosophers alike. As with so much of our evolutionary thinking, we go back to Darwin and the Origin of Species , and the ideologies of his “one long argument,” as a starting point. Darwin (1859, p. 477) was well aware that ecology is important in shaping the evolution of life—“the relation of organism to organism is the most important of all relations”—but, perhaps more importantly, he realized the consequences of such a view for the history of life (see Ghiselin, 1995). Today, this Darwinian view of the evolutionary process, hardened by the architects of the Modern Synthesis, argues for long-term directionality in evolution. Directionality is the consequence of ecological struggles among metabolizing entities with energy-intensive forms of life exacting primary top-down control over, and replacement of, less energetic forms (Vermeij, 1999). This inherent directionality in the history of life, however, does not imply that living species, with more specialized and energy-demanding adaptations, are “better able to cope” with their biological environment than species in the geologic past were with theirs (Vermeij, 1987, p. 421). The most sophisticated modern version of Darwin's view of the efficacy of biological agents of selection, and, to me, arguably one of the most significant paleontological hypotheses of the last 25 years, is Geerat Vermeij's (1987) hypothesis of escalation, which states that the history of life has been characterized by two simultaneous long-term directional trends within similar environments: increasing biological hazards (predation and competition), and increasing incidence and expression of enemy-related adaptations to these biological hazards. In the limited space of this essay, I will attempt first to define briefly what is meant by escalation, stress two of the …