ABSTRACT
Adequate food, water, and shelter are basic to human survival. Closely linked to these life essentials is an adequate energy supply, for humans have always used energy to obtain food, water, shelter, and protection from parasites and predators. Over the centuries people have employed energy from many sources. First they depended on their own energy and natural energy from sunlight; later they relied on re, draftanimal power, and water and wind power. Still later they invented engines fueled by wood, coal, petroleum, and, more recently, nuclear energy. Humans have used these various energy resources to modify and manipulate land, water, plants, and animals to ful ll their survival needs. Finding, controlling, and using energy has enabled humans to progress from an unsettled, primitive lifestyle to a more settled and sophisticated lifestyle. Among the mammals, only the humans can think creatively and develop advanced technologies.
