In 1980, University of Maryland economist Julian Simon bet Stanford entomologist Paul Ehrlich that the price of any five metals of Ehrlich's choosing would fall over 10 years. Ehrlich believed that resources would become scarcer over time as population grew, while Simon believed that people would find good substitutes, just as earlier people developed iron as a substitute for scarce bronze. The price of all five metals that Ehrlich chose (nickel, tin, tungsten, chromium, and copper) fell over the next 10 years and Simon won the bet. Ehrlich, an honorable man, sent a check in the appropriate amount to Simon.

The falling price indicates that the metals are either more or less scarce than they were before. If it was discovered that the quantity also fell for the five metals over the ten-year period then they would increase or decrease in supply or demand most likely caused the changes in price and quantity.