The central theme to Charles Mann's 1491 is that what we call pristine wilderness today is a European creation. The landscapes of the North America, Central America and the Amazon were terrascaped by fire and farming. When small pox hit the indigenous populations it removed the inputs that the local humans had used to maintain a stable ecosystem. Without the US North-East being burnt periodically the mast farms disappeared. Without the slash and char (not burn) method of farming the Amazon forest grew back to cover up the human planted fruit forests under the canopy that spread across the Amazon. (more)