Rabbits were introduced to Australia and New Zealand as a source of food, and their population then grew explosively. Because they had few natural predators and competitors there, they spread quickly and became one of the most damaging feral pests in both countries. They strip vegetation, compete with livestock and damage crops, and contribute to soil erosion. Authorities later tried biological controls, including the deliberate release of myxomatosis in Australia in 1950. The story is a textbook case of an unintended consequence, where a well-meant introduction created a long-running ecological problem.

In 1909 D. W. Griffith made a 14-minute film about a speculator who corners the wheat market and doubles the price of bread. A farmer sows his field while a 'Wheat King' gambles in the Chicago wheat pit; bakers raise the loaf from five cents to ten and the poor line up for bread. Griffith cut back and forth between the farm, the feast and the breadline, a technique called parallel editing, so audiences saw both ends of the economy at once. The film drew on Frank Norris's stories and on a real scheme: months earlier Chicago financier James Patten had cornered wheat, sent bread prices up and made about $5 million, roughly $185 million today.