Darwinism After the Modern Synthesis

Abstract

The Modern Synthesis in evolutionary biology took place in two major phases from the 1920s through the 1940s. It achieved a reconciliation between the original Darwinism and the newly discovered Mendelism, which gave birth to the field of population genetics, the mathematical core of evolutionary theory. Since that time, the field has further evolved, encompassing entirely new areas of inquiry, leading to new empirical findings, and developing new conceptual tools. In the 1960s, for instance, the invention of gel electrophoresis made it possible for the first time to directly estimate gene frequencies in natural populations. While developmental biology was initially still excluded from the synthesis, in the 1980s new techniques led to the emergence of the field of evolutionary developmental biology (evo-devo). The parallel molecular revolution unfolded initially independently of evolutionary studies, until the turn of the twenty-first century, when genomics became “comparative” in nature and began importing techniques from phylogenetic analysis. The reevaluation of phenomena like phenotypic plasticity and epigenetic inheritance led to a rebirth of interest in the complexities of the genotype–phenotype map, triggering the formulation of concepts like robustness, modularity, and evolvability. Paleontology came roaring back with the theory of punctuated equilibria in the 1970s and 1980s. These many strands brought about the need for a further expansion of evolutionary theory, catalyzing discussions concerning a possible Extended Synthesis. “Darwinism” has never been more alive and pregnant with opportunities for both theoretical advancements and philosophical reflection.