What would become of the world if there was no Love?
Some may not understand what I mean by Love (heck, the way it's used is a butchering of the word) but it isn't lust, and isn't necessarily romantic love. Love encompasses brotherly love, the love of a family etc.
-
Well, love is mostly caused by the release of seretonin in our brains. Seretonin regulates mood. In doses that are too high or low, you will be more impulsive. No dopamine would be more detrimental to our survival, as it motivates us to do things such as seek information, accomplish tasks, and even eat.