ABSTRACT
The evolution of human societies has been dependent upon the conversion of ever larger amounts of ever more concentrated and more versatile forms of energy. Life on Earth, the only known life in the universe, would be impossible without the photosynthetic conversion of solar energy into plant biomass. Humans depend on this transformation for their survival and on many more energy flows for their civilized existence. From the perspective of natural science, both prehistoric human evolution and the course of history may be seen fundamentally as the quest for controlling greater energy stores and flows. Human dependence on ever higher energy flows can be seen as an inevitable continuation of organismic evolution. Living organisms— from the smallest bacteria to the largest civilizations—temporarily defy this trend by importing and metabolizing energy.
