The invention of the bow and arrow allowed users to shoot projectiles more rapidly and more accurately than with the traditional spear. A new theory argues that this innovation resulted in more than just a technological revolution. It also had profound social consequences wherever the bow was adopted. Stony Brook University biologists Paul Bingham and Joanne Souza developed the “social-coercion hypothesis” as an explanation for the rise of social complexity. They recently outlined their work in the journal Evolutionary Anthropology. According to this idea, the introduction of a more-effective weapon system gave social groups a safer, more-reliable way to coerce...