"Two Last Thoughts If you had to boil this book down to a single phrase, it would be "It's complicated." Nothing seems to cause anything; instead everything just modulates something else. Scientists keep saying, "We used to think X, but now we realize that ..." Fixing one thing often messes up ten more, as the law of unintended consequences reigns. On any big, important issue it seems like 51 percent of the scientific studies conclude one thing, and 49 percent conclude the opposite. And so on. Eventually it can seem hopeless that you can actually fix something, can make things better. But we have no choice but to try. And if you are reading this, you are probably ideally suited to do so. You've amply proven you have intellectual tenacity. You probably also have running water, a home, adequate calories, and low odds of festering with a bad parasitic disease. You probably don't have to worry about Ebola virus, warlords, or being invisible in your world. And you've been educated. In other words, you're one of the lucky humans. So try. Finally, you don't have to choose between being scientific and being compassionate. Abbreviations in the Notes In order to save forests' worth of paper, references cite only the first one or two authors."