Horses only 15 inches high, 141 tree species in a single acre of tropical rain forest—what spectacular variety we see among living things, both variation within kind and the stupendous number of different kinds.

An intriguing development in recent evolutionary thought has been the growing repudiation of neo-Darwinian orthodoxy (that is, the idea of slow and gradual evolution, accomplished by the mechanism of small random genetic mutations preserved by natural selection) in favor of the idea of rapid evolution caused by rapid environmental changes.

The Uniformitarian Century

In the early days of geology, especially during the 17^th and 18^th centuries, the dominant explanation for the sedimentary rocks and their fossilized contents was that they had been laid down in the great Flood of the days of Noah.