Extinction at the K-T Boundary Summary

The narrator reflects on the history of the modern scientific debate over the subject of extinction. In 1786, Baron Georges Cuvier first demonstrated that species became extinct. When Darwin set forth his theory of evolution many years later, there was very little debate. Scientists simply saw extinction as the failure of a species to adapt. However, in the 1970s, as mankind's technological prowess advanced at an alarming rate, scientists began to wonder if humanity's behavior could ultimately lead to extinction. Scientists began to study the extinction of previous species, looking for answers.

In 1980, physicist Luis Alvarez discovered high levels of iridium in the earth at a point called the K-T boundary. The presence of iridium in this layer is suggestive of a giant meteor from space, and it supports the theory that the dinosaurs of the...