At what point did man stop being a part of nature. In the beginning, man was just another inhabitant of the natural world. One of many organisms trying to survive and prevent from being eaten. Man used to prey other other animals and plants and were preyed upon themselves. No greater affect on the environment than anything else on the planet. But, somewhere along the line, we evolved developed more than any living creature.
Early man became aware of what he could do. He was not as limited as he once thought. The use of tools put us above the rest and we made changes with these tools. Before you know it, we were manufacturing products and building skyscrapers. Not to mention, using up sizeable amounts of resources, creating waste well beyond our means to control it, creating discord with our fellow planet residents, and forever altering our surroundings.
And here we are today, trying to save the planet from ourselves and reducing our impact on the world we live in. Maybe the easiest way to do that would be to go extinct and let nature take over once again.