Yes and no, depression hasnt been around long enough. The problem is that most "depressions" are a result of modern behaviour: 1. having the wrong diet. Not enough fish, nuts, vegetables, fruits, insects etc. 2. most of the foods in for example supermarkets look perfect but dont contain enough nutrition. We try very hard to eat healthy but if the foods presented dont contain the proper nutrition the onset of disease is only a matter of time. 3. We have too much time on our hand to think. We see the news and bad news sells better than good news, guess what kind of news you will see. Guess why you start your day irritated. 4. Our brain has to process more information than we used to. A sheepherder in Siberia has less to worry about than somebody who has internet, tv, radio, car radio, gsm, vcr, dvd, pc. He uses and needs less Serotoninne for example. He has a higher intake of vitamine b relative to his usage. 5. Our surroundings have changed too much, we are (simply put) still monkeys, but monkeys who live in concrete boxes and drive metal objects. People need more excercise and "greener surroundings". 6. We are with to0 many of our species. We almost never have a clear mind without concerns or irritations from people in our direct surroundings. The "family" or "clan" we belong to (country or continent) is simply too big. This is for example why hooligans bunch togheter to fight. They need a small clan to prove themselves. So the answer is (I think) YES because depression can make the human species aware of these (future) problems. And the answer is also NO because the people who suffer from depresion dont really fit in our society any more. ps I also think the mix of gasses in the air we breath has changed and continues to change as well. I believe years ago there was an experiment in wich an increase in for example carbondioxide (+2%) caused all of the testpersons in an experiment to show anxiety symptoms wich are often related with depression. In short; we are with too many in a small "greenhouse" in space.... Depressed people are almost always right, but positive people have the whole world.