The principle of sustainability is the answer We humans are the dominant species on our planet, but many people have begun to wonder how long that will be the case. As you have read in this chapter, by our sheer numbers and many of our activities we have disturbed many, if not virtually all, ecosystems on the planet. That course cannot continue for much longer. Fortunately, governments and individuals are beginning to embrace the principle of sustainability. This principle is simple: controlling our population growth, using resources wisely, embracing renewable energy sources, and protecting the wild places where other species live, we will be taking steps that help ensure our own survival as well