~Human nature~

Alrighty, so I'm pretty useless at doing more than one thing at a time which is why I have verryyy little blogging material to actually show for myself. BUT it is now a Saturday night therefore I can type to my heart's content without waking up in the morning thinking "Shit, I've only had two hours sleep."
So this week I've kinda been thinking about human nature and what makes us the way we are - I mean, why we're so different from the animals that surround us. I'm an atheist so don't tell me God made us like this because, personally, I couldn't give a crap.
So, in my view anyway, we were all once part of nature - whether we were monkeys or frogs, who knows for sure? But anyway, what I'm trying to say is this: how can we have adapted and evolved so much that it is now a part of human nature to want to destroy? To be honest, this all came after watching Avatar last weekend (if you haven't watched it yet do it now. it's amazing. and yes I know I sound like a mega-geek but screw you.). It suddenly struck me how violent humans are as a whole.
And I mean, yeah, we could get into the whole "Animals kill things too. It's all part of life bla bla bla..." discussion but animals don't go around ripping up forests and flattening out land to make way for houses or cutting down trees just so DFS can make more furniture.
I really am useless at explaining but what I'm trying to make a point of is that we've ended up on the opposite side of where we started - we've turned against what actually brought us into being in the first place. By constantly changing and finding new ways to power this and new things to make that with we are obliterating our own roots.
But the most annoying thing for me is that it's never going to stop because, let's face it, given the option would you rather be around now with mobiles and internet or back in earlier times when everyone was content with what they had.
Or maybe that is the problem with humans - we are never content, we are always strivng to become better. Is it a problem? I don't know. I've managed to confuse myself now. Help?