Contingency in evolutionary biology refers to how very small changes can lead to profound effects, such as the asteroid that wiped out the dinosaurs and paved the way for the rise of mammals. On the other hand, convergence in evolution is about stable patterns emerging under pressures, like the similar evolution of octopus and human eyes due to the limited ways vision can work. This framework extends to human social change, where small events can significantly alter history. Contingency is exemplified by events like hitting the snooze button and facing a life-altering car accident, while convergence reflects events that do not significantly impact the course of life. This concept applies both to individual lives and societal changes.