Littered througout Charles Darwin´s works are illusions to extreme sickness, uncomfort, and even depression. He confesses to fits of "hysterical crying" and "not being able to do anything one day out of three." However, like most people of his time and even today, he neither saw nor attempted to see any benefit or goodness that came from this depressed state of mind. In continuing with the Darwin example, he himself admits that "work is the only thing that makes life bearable to me" and was his "sole enjoyment in life." Potentially there was something in depression that Darwin did not see?
Researchers at the University of Virginia have been examining this exact idea. Why, for example, is depression so common among the population if it should supposedly be selected against in reproduction? Researchers estimate that every year more than 7% of people will be affected by depression, making it as common as the cold. The answer to these researchers is that depression has some secret purpose, and that humans may not suffer in vain.
While the idea is still a very new and unproven idea, many scientists now think that depression can focus a brain to achieving greatness in a way that those without cannon. In the fourth century BC, Aristotle was one of the first to note that "men who have attained excellence have also suffered from melancholic disease." Researchers in Virginia have hypothecized that this inability to become distracted in everyday pleasures such as food, friends, or sex might have led these depressed people to become more focused on the pressing problem of the time - an example in which Charles Darwin fits right in.
Regardless of the causes or supposed benfits of modern and not-so-modern depression symptoms, we know that it is a disease that is extremely abundant in the modern population, and this does not fit with the theory of natural selection if it is truly a genetic trait and truly a detriment to an individual´s life.