Late in September of 1838 Charles Darwin read a book by Robert Malthus, and discovered natural selection. Darwin, then 29 years old, was the Secretary of the Geological Society of London. Malthus, who had died two years previously, had been the first professor of economics. The interdisciplinary relationship may serve to remind us of two very important points. First, Darwin transformed biology into an historical science, in the sense that geology is an historical science. Second, Darwin transformed biology into an economic science, by showing that the natural economy and the political economy are variations upon a common theme (Hirshleifer 1978).