Dawkins, Richard. The Selfish Gene. Oxford University Press, New York, 1976.

---. The Blind Watchmaker. W. W. Norton & Co., New York, 1987. These two books by Dawkins, both eminently readable, present a modern view of the evolution of genetic systems.

Goodwin, Brian C. How the Leopard Changed Its Spots: The Evolution of Complexity. Charles Scribner's Sons, New York, 1994. About the evolution of morphology.

Gould, Stephen Jay. Bully for Brontosaurus: Reflections in Natural History. W. W. Norton, New York, 1991. One of Gould's popular collections of essays on natural history and evolution.

Huxley, Julian. New Bottles for New Wine. Chatto and Windus, London, 1957. Essays about evolution, population, and other important biological matters.

Irvine, William. Apes, Angels, & Victorians: The Story of Darwin, Huxley, and Evolution. McGraw-Hill Book Co., New York, 1955.

May, Robert M. "How Many Species Inhabit the Earth?" Scientific American, October 1992, p. 18. Anywhere from 3 million to 30 million may inhabit the earth, according to various estimates, and an accurate census may be crucial for efforts to preserve biodiversity.