LAUSR

Significance Mechanisms of emergence and early diversification of structured proteins present deep and difficult problems in evolutionary biology. Here we excavate the deepest evolutionary history, found within the translation machinery, which is an ancient molecular fossil and the birthplace of all proteins. We provide evidence supporting common origins of some of the simplest, oldest, and most common protein folds. The data suggest a mechanism, that we call creative destruction, that explains at molecular level how old folds spawn new folds. In this mechanism, new folds emerge from old folds via gene duplication, protein expression, exploration of new folding landscapes, and adaptation. Creative destruction explains the facile emergence of complex from simple architectures in a funneled exploration.