One of my favorite questions to ponder:
If trees could scream, would we still cut them down?
...It's a very interesting question, and I'll even take it a step further. How exactly do we know they can't scream? We don't know that. Perhaps they scream on a frequency we humans do not have the capacity to hear. Perhaps they have alternate ways of expressing their pain. Are we that arrogant to assume if the human ear cannot hear something, the sound must not exist?