In 1980, two American professors bet $1,000 on a question with stakes  that couldn’t be higher: would the earth run out of resources  to sustain a growing human population? One of them was Stanford biologist  Paul Ehrlich, who wrote the bestselling 1968 book, “The Population Bomb.” The global population had grown rapidly since World War II, and Ehrlich predicted that millions would starve to death as the population increased faster than the food supply. He drew from the ideas of 18th century economist Thomas Malthus and related work from the 20th century. Malthus had posited  that population growth, if unchecked over time,  would always outpace food supply. Through the 1970s,  it seemed like Ehrlich was right: famines, pollution, and political unrest had many concerned that humanity  was on the brink of such a crisis, and some governments considered  and even implemented policies to limit population growth. Betting against Ehrlich was Julian Simon, a professor of business and economics. He analyzed historic data from around the world, and found no correlation  between a growing population and a decrease in standards of living— in fact, he found the opposite. He argued that Ehrlich’s work, and that of Malthus before him, was based on theoretical calculations, while the real-world data told a different story. But then, he departed  from the data himself, claiming human ingenuity would always find alternatives to compensate for diminishing resources. If that seems overly optimistic to you, well, you're not alone. Ehrlich and other experts found  Simon’s claims preposterous. In June 1980, Simon wrote a scathing  article for Science Magazine that incited a heated debate of published  articles between the two men. Simon said he should have placed a wager against Ehrlich years before, when Ehrlich ventured that, “England would not exist  in the year 2000.” Later that year,  Simon called Ehrlich a false prophet and challenged him to a bet. Their feud also touched on the debate about whether to prioritize environmental protections or economic growth, a key issue in the American presidential race between Jimmy Carter and Ronald Reagan. After some debate, they set the final terms: $200 on the price of each of five metals. If the price of the metal decreased  or held steady over the next decade, Simon won. If the price increased, Ehrlich won. Wait, what? Weren’t we talking  about overpopulation and famine? What could the price of metals possibly have to do with that? Well, the reality is that the price of metals may not have been the best choice— many factors impact these prices that have nothing to do with overpopulation. But their reasoning was as follows:  metals are finite natural resources used in all sorts of manufacturing. Ehrlich believed a growing population  would consume such finite resources, and scarcity would drive the prices up. Simon thought humanity would find substitutes for the metals, and the prices would stay stable  or even decrease. So, what happened? The world population continued  to increase over the next 10 years, but the price of all five metals  decreased, making Simon the clear winner of a bet that may not have been a great proxy for the question they were debating, anyway. As for the question itself, today, their focus on overpopulation represent a snapshot of history. Our understanding of what causes starvation and famine has progressed: we have the resources to support a growing human population, but we’re currently failing to distribute those resources equitably, and changing that should be our priority. And we no longer see population size  as a primary cause of environmental degradation  and climate change, or limiting population growth  as a viable solution to these problems. Rather, experts largely agree that our focus should be on replacing unsustainable technologies and practices with sustainable ones, and that economic growth  and environmental protections don’t have to be at odds. In October 1990, Julian Simon  received a check from Paul Ehrlich. There was no note.