Just because something is not aware as us, does not lower it's significance any less then a human. Yet this, is not the true.
Today, I killed a spider, I'm afraid of spiders. I killed him without regard of it's life, since it negatively effected me I destroyed it. Then I condone my action by my feelings towards it.
If in this situation, a human cannot acknowledge life, then what is the difference from a human killing another human? Just because it's a human that makes it's death highly more significant then that of a bugs? There is a moral ideal behind this, and until people acknowledge it I don't think we can ever stop harming each other, if we on small scales kill things just because we don't like them.