Posthing this again as you seem to respond to every post but mine.

I don't kill spiders out of ignorance, and even if I did, it has nothing to with being civilized or not.

I understand you (and with you, I mean everyone) are motivated to believe we are an advanced race but we're still just automatons for the most part. When we feel threatened and there is no negative consequence for us, we kill the threat. It's that simple. Irrational or not, doesn't matter. And yes, my life is more valuable than a spider's. It's also more valuable than yours. In fact, it's more valuable than any other life I know of. And yes, I feel threatened by large spiders. There is no negative consequence for me to kill it. 1+1=2. I kill the spider, and that's all there is to it.

I don't think we are any better than others, that's the point.  That said, most humans DO truly believe that they're a higher, more enlightened life form, so by that logic they should know better than to kill mercilessly out of fear, like so many do.  if people want to be convinced of their own superiority, they should earn it. prove it by acting enlightened rather than just saying you are.  Logic tells me theres no reason to kill something that has done nothing to harm you, can do nothing to harm you, and has no intention of doing anything to harm you.  Unless it's one of them Brazilian Wandering Spiders, those things can kill, in which case self defense applies. 

My philosophy is simple, NEVER kill anything unless it's for your own survival, be it to eat or in self defense. pretty simple philosphy, pretty fair, pretty all-encompassing.