Modern Synthetic Theory of Evolution

Darwin's original 1859 theory of evolution by natural selection was, in its own time, a genuinely revolutionary and largely correct account of HOW favourable heritable variations spread through a population over successive generations — yet Darwin's theory, as originally formulated, contained one significant and important gap. Darwin himself, writing several decades before Gregor Mendel's foundational work on the genetics of the garden pea was rediscovered and widely appreciated by the broader scientific community (in 1900, some eighteen years after Darwin's own death in 1882), had no correct understanding of exactly HOW heritable variation actually arose among individuals of a population in the first place, nor any correct understanding of the precise physical or chemical mechanism by which parental characteristics were transmitted to offspring — Darwin, like most biologists of his own era, still worked with a vague and, as later genetics would show, largely mistaken notion of 'blending inheritance', in which offspring characteristics were assumed to represent some averaged blend of their two parents' characteristics.

The Modern Synthetic Theory of evolution, developed collaboratively by a number of biologists, geneticists and statisticians chiefly during the 1930s and 1940s, closed this important gap in Darwin's original theory by bringing together Darwin's own central insight of natural selection with the substantial body of twentieth-century scientific knowledge that had accumulated in several closely related fields since Darwin's own time: Mendelian genetics (the rules governing how discrete hereditary factors, now understood as genes, are transmitted from parent to offspring), population genetics (the mathematical study of how allele and genotype frequencies change within populations over successive generations), palaeontology (the ongoing study of the fossil record), and systematics (the science of classifying organisms based on their evolutionary relationships). This unified framework is called a 'synthesis' precisely because it does not represent any single new discovery, but rather the deliberate combination — the synthesising together — of several previously separate scientific fields into one coherent, mutually reinforcing theoretical framework. …