Summary

In an experiment in 1948 conducted by two Harvard psychologists, student subjects were asked to identify abnormal playing cards among normal cards. Among the doctored cards were ones with “red spades” and “black diamonds.” When the cards were displayed rapidly, these doctored cards went unnoticed. When the cards were revealed more slowly, they students tried to explain what they were seeing but were largely confounded. Science historian Thomas Kuhn found that the study confirmed his belief that people try to justify misinformation when first confronted with it. In the world of science, accepted theories are defended when contrary evidence is initially presented. A paradigm shift takes place when someone is bold enough to accept the new data.

The history of the science of extinction went through a series of such paradigm shifts. “Extinction” didn’t exist until the end of the 18th...