For hunters and gatherers of the paleolithic era, these relationships shaped every moment of their lives. They lived in the natural world. They depended directly on its bounty. And they normally thought of themselves as a part of the natural environment. But as humans developed more and more powerful technologies, they began to extract more resources and energy from the natural environment. Farmers found that by cultivating the land and by domesticating animals and plants, they could produce far more food from a given area of land. As populations grew, humans got better and better at extracting more resources from the natural environment. Today, we control as much as 40 percent of the energy available to support life on earth. But the more timber, food, water, and fuel we take from the natural environment the less is available to other species. Our impact becomes greater and greater on other animals and plants, on the world’s oceans and waterways, on the air, and on the land. Today, our impact is so great that we are in danger of undermining many of the natural systems on which our lives depend.

Understanding our changing relationship with the environment is, therefore, at the core of historical understanding. It involves grappling with questions of how humans have lived, how they have treated the earth, and how their power over the earth has grown. Understanding the changing relationship between humans and the environment in the world's past may be a first step towards finding a less damaging relationship in the future.