For many of us the threats of predators — lions and bears, say — are long gone. Yet most animals face these pressures on a daily basis. The common pests in your garden or farm are no exception. Simply the threat of predation can greatly shape an organism’s behavior, internal function, and even what it looks like. For example, pea aphids that are exposed to predators are more likely to produce offspring that have wings (Weisser et al 1999).