Just kidding about the stupid, that was just to grab your attention ;-)
If you think of the human race as a collection of members that rely on each other for their survival, you start to understand the rather fluffy word “Love”. How do we rely on each other? Human babies require longer nurturing than most species before they can survive independently. Human institutions rely on information passed down generation after generation to keep a knowledge base growing to advance human discoveries in favor of survival, much like they’ve shown even monkeys will do (http://en.wikipedia.org/wiki/Hundredth_monkey_effect). School/education is highly prized by society, which requires learning from others. Humans regularly form business partnerships, marriage arrangements, and settle into cities where social services provided by other people are abundant: other people pick up your trash, fix the roads, provide health services, entertainment, anything you may want or need. We depend on each other strongly to thrive. It is hard to even imagine life independent of other people. Such people are considered outcasts by society and are not looked favorably upon. We need each other and depend on one another. We light up each other’s chemicals and release feel-good, healthy signals in each-other. The recognition and flourishing within this system of survival is what we call Love.