In 1968, Ehrlich published The Population Bomb, which argued that mankind was facing a demographic catastrophe with the rate of population growth quickly outstripping growth in the supply of food and resources. Simon was highly skeptical of such claims, so proposed a wager, telling Ehrlich to select any raw material he wanted and select "any date more than a year away," and Simon would bet that the commodity's price on that date would be lower than what it was at the time of the wager.
Ehrlich and his colleagues picked five metals that they thought would undergo big price increases: chromium, copper, nickel, tin, and tungsten. Then, on paper, they bought $200 worth of each, for a total bet of $1,000, using the prices on September 29, 1980, as an index. They designated September 29, 1990, 10 years hence, as the payoff date. If the inflation-adjusted prices of the various metals rose in the interim, Simon would pay Ehrlich the combined difference. If the prices fell, Ehrlich et al. would pay Simon.
Between 1980 and 1990, the world's population grew by more than 800 million, the largest increase in one decade in all of history. But by September 1990, the price of each of Ehrlich's selected metals had fallen. Chromium, which had sold for $3.90 a pound in 1980, was down to $3.70 in 1990. Tin, which was $8.72 a pound in 1980, was down to $3.88 a decade later.
As a result, in October 1990, Paul Ehrlich mailed Julian Simon a check for $576.07 to settle the wager in Simon's favor.
