Summary

Although Darwinian concepts of evolution and adaptation explain many aspects of life and its dynamism, they do not explain the origin of life itself. The same holds true for the origins of the universe. While evolutionary changes are gradual and slow, changes caused by extraterrestrial intervention in the form of a colliding asteroid or meteoroid are sudden and unpredictable. The dinosaurs, for example, had evolved over time into many subspecies and types when they were largely wiped off the face of the earth by the cataclysmic event of 66 million years ago.

"It is easy to forget how dependent our existence is on the many contingencies that allow life to form and to die out," Randall says. "Extinctions connect our planet to meteorological events in both senses—weather and outer space." Life itself started on earth about 3.5 billion years ago. Photosynthesis emerged about...