The first and second Industrial Revolutions vastly increased farm productivity, thus increasingly freeing the labor force to work in other occupations. By eliminating farming as the main occupation of Americans, as the chart shows, these inventions eventually led to the liberalization of sexual mores and the emancipation of women. Agricultural societies need child labor, so fertility is all-important. Anything that interferes with childbearing, such as divorce, homosexuality and abortion, is strongly discouraged.
A widespread notion is that computers, the Internet, nanotechnology, bioengineering, and so forth represent a fundamental change in human affairs. These recent inventions are sometimes hailed as a "third Industrial Revolution." The first Industrial Revolution--roughly spanning the 1770s to 1860s--saw the development of the steam engine, steamboat, locomotive, telegraph, cotton gin and steel plow. The second Industrial Revolution--from the 1870s to the 1910s--witnessed the invention of the telephone, internal-combustion engine and electric lightbulb as well as the germ theory of disease, movies and radio.