Abstract
A central question in the fields of genetics and evolution was the nature and origin of spontaneous mutation. Bacterial genetic experiments throughout the middle of the 20th century were key to understanding how genomes change and what cellular mechanisms act to limit such change. These mechanisms are shared among all life on the planet and have implications for human diseases and aging. The purpose of this review is to highlight genetic breakthroughs during this period using bacterial systems and how they have led to our understanding of genetic change. Many students of cancer genetics in humans are likely unaware of the foundational role of bacterial genetics in our understanding of spontaneous mutation and cellular avoidance mechanisms that impact cancer progression. This article attempts to provide an overview of critical experiments and hypotheses.