Neo-Darwinism, Expansion, and Consolidation (1900–1980)

Abstract

The twentieth century saw neo-Darwinism absorb its competitors and coalesce into the Hardened Modern Synthesis. Vernon Kellogg helped usher in this new era with Darwinism Today, proclaiming in 1907 that Darwinism was of critical historical importance but little actual scientific value and anticipating that new experimental and mathematical data would resolve the struggle among competing frameworks to replace it. Kellogg was prescient in proclaiming that the core question was how the right adaptation always arose at the right time, which became the major focus of twentieth-century evolutionary biology. Darwin’s notion that preexisting variation was the fuel for coping with environmental change was abandoned in favor of something more heroic and aspirational, satisfying the ultramodernist styles of the time. In the ensuing decades, neo-Darwinian pan-adaptationism became the Modern Synthesis, permeating all corners of biology, especially ecology and behavior. By the 1980s, the Modern Synthesis hardened further. Natural selection was entrenched as a sharp-edged tool rather than Darwin’s blunt instrument; a creative force from which function follows the conditions and form follows function. The Nature of the Conditions became the dominant explanation for everything, the Nature of the Organism relegated to an epiphenomenon. Evolutionary explanations became increasingly ecological and ahistorical, focused on how every trait was an adaptation to the conditions, and how the conditions were structured to accommodate organisms in the form of preexisting niches or zones. Seventy-five years on, Darwinism seemed to be as dead as Kellogg asserted.