Geologist Keith Miller examines the "Cambrian Explosion", a period of rapid evolutionary diversification approximately 575 million years ago, and whether it poses a challenge to evolutionary theory.

“I flatter myself,” Hume triumphantly proclaimed, “that I have discovered an argument . . . which, if just, will, with the wise and learned, be an everlasting check to all kinds of superstitious delusion, and consequently, will be useful as long as the world endures.”