Optimization and chance in the progenote era
The proliferation of life depends on a process of open-ended evolution that continuously produces novel and adaptive forms. In terrestrial life this process is sustained by functional polymers. There are several evolutionary mechanisms by which polymers can acquire and improve their functions. These include mechanisms supported by insertion, deletion, point mutation, duplication, and recombination. Identifying how different evolutionary mechanisms drive innovation, and establishing their impact on the relative contributions of optimization and chance in this process, is fundamental to understanding biology. I will discuss multiple mechanisms of evolutionary optimization and examine the extent to which they were operational in the progenote era (i.e. the time prior to the emergence of a precise and accurate connection between genotype and phenotype). I will highlight ongoing work in the Origins Research Group at NASA Ames that combines in vitro evolution with structural, biochemical, and computational analyses to gain new insights into the evolution of the earliest forms of life.