Technology has been a primary driver of social change for thousands of years. In particular, four technological innovations were responsible for social revolutions: The domestication of plants and animals over ten thousand years ago, the invention of the plow, the invention of the steam engine, and the invention of the computer all led to massive social change (Henslin 390). The transition from hunting and gathering to a pastoral society changed earlier societies by enabling them to abandon migratory practices and establish fixed residences. The invention of the plow revolutionized agricultural techniques and increased yields, allowing societies to sustain larger populations. The invention of the steam engine in the 18th century transformed the transportation capabilities of society and spurred further innovation as people and materials could be quickly transported on land for distances previously unimaginable. Finally, it is difficult to understate the ways in which the microchip and personal computer have fundamentally altered the organization of society; the instant access to and constant flows of information have changed communication, education, and business in modern society. In light of the social change wrought by these technological innovations, sociologist William Ogburn argued that technology was the basic cause of social change. In particular, he identified three processes by which technology drove social change: Invention, discovery, and diffusion. While invention can refer the combination and transformation of existing materials into new items, it can also refer to social invention and the propagation of new ideas. The aforementioned invention of the plow is one example of a physical invention, but the invention of economic and political systems are also types of social invention. The second process of social change – discovery -- refers