EXTINCT IN THE WILD

For every species that is alive today, perhaps a thousand more have lived previously and become extinct. Most of these extinctions occurred before humans evolved, and the species are known to us only through fossils.

Extinctions are a natural part of evolutionary processes, but through most of the history of life on Earth, biological diversity has been increasing. Periodically, however, major changes in the conditions on Earth have caused the collapse of living systems, and large percentages of species a have become extinct. These species will never return. See Spotlight on Extinction »