Modern Synthesis Review

For well over half a century, the Modern Synthesis served as the bedrock of evolutionary biology. By reconciling Mendelian genetics with Darwinian gradualism, the paradigm established a deterministic continuum: random genetic mutations alter nucleotide sequences, changing the amino acid order of translated proteins. These primary chains fold into rigid, stereochemically optimized three-dimensional structures. Natural selection then acts as an unrelenting thermodynamic and functional sieve, penalizing deleterious missense mutations that destabilize these native architectures while rewarding rare, advantageous conformational shifts. Central to this neo-Darwinian architecture was the foundational dogma of molecular biophysics, the lock-and-key paradigm established by Emil Fischer and later codified by Christian Anfinsen: sequence dictates unique three-dimensional structure, and structure dictates function. The discovery and functional characterization of intrinsically disordered proteins ...

The classical framework of molecular evolution has long rested upon the sequence-structure-function paradigm, a conceptual cornerstone inherited from mid-twentieth-century biochemistry and integrated into the Modern Synthesis. In this traditional view, natural selection acts to preserve specific, rigid three-dimensional protein folds necessary for precise biochemical catalysis and binding.  Intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs) which lack a stable tertiary architecture under physiological conditions were historically regarded as evolutionary anomalies or flexible linkers evolving under neutral drift or severely relaxed purifying selection. However, modern computational and evolutionary analyses, prominently exemplified by the study "Evolutionary Forces and Codon Bias in Different Flavors of Intrinsic Disorder in the Human Proteome" by Sergio Forcelloni and colleagues (2020), have upended these simplistic assumptions. By...