and you're looking to explore further, I would love to recommend a couple authors on this very subject - namely, the issue of "the natural world exists for the benefit of human beings."
Definitely read Daniel Quinn's Ishmael trilogy - (1) Ishmael, (2) The Story of B & (3) My Ishmael. You may find the presentation somewhat annoying and elementary, but one has to assume that Quinn's intention was to present the philosophy contained in the book with mass appeal (understanding, comprehension).
Also Derrick Jensen - one of the most amazing writers I've ever read. His "A Language Older Than Words" is his first, and probably has more of a direct relevance to the issues you raise, but if you read it and like it, you must read his follow-up, "The Culture of Make Believe". Fucking fantastic. I've never cried while reading a book, but Jensen definitely made me well up a few times.
Both Quinn and Jensen are essentially secular humanists, or animists. Please read them, I promise you'll be glad you did. I'd love to hear what you think of them. I'm pasting a review of "The Culture of Make Believe" below from Amazon to give you an idea, because I thought it was good. And a link...
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Had I grown up in Nazi Germany a soldier, would I have aided the genocide? I would like to think that I would have protested the slaughter by working underground with escapees. However, I might have been a totally different person. Perhaps the harsh SS training would have turned my heart into an icicle, filled my head full of propaganda, and habitualized my body to subordination. Perhaps I would have been a willing executioner. Perhaps it would have been impossible for me to lift my consciousness above the zeitgeist - not many did.
Hindsight, as they say, is 20/20. Understanding the present is much more difficult. Could it be that colonialism, imperialism, the KKK, and every other boot-licking, world-plundering, cold-blood-murdering institution somehow mutated and merged into one New World Order bent on killing the planet and everything/-one that stands in its way? Moreover, if one were raised inside such an institution, believing it completely natural, and even being rewarded for participation in its mundane work-a-day activities, would it be possible for that person to awake to the insanity of their culture?
Along with all of us, Derrick Jensen grew up inside such a culture, realized what was happening, and wrote this book to tell other potential executioners what is going on. Reading The Culture of Make Believe is like looking into the mirror of our culture, and chances are you will not like what you see. I'm not saying this to rub it in your face, but to give a word of caution. Let me to be more explicit. If you are able to accept new information into the ken of your mind, this book will radically alter your perception of reality. You might not be able to live the same way there after. It's like having the psychological sanity rug pulled out from under you - or blasted to pieces. Upon finishing, you will feel as if you had a full-frontal lobotomy, or as though you just swallowed a gallon of hydrochloric acid. That's the aftertaste of Western Civilization - no frappacino.
Sounds ambitious, most people would agree. I imagine submitting Jensen's thesis to Ph.D. advisors. "What's your topic?" they'd ask. "I want to write a critique of Western Civ." After a giggle, they would reply with something like, "Sorry, it's too broad. Narrow it." Well, if you count A Language Older Than Words (the thematically congruent if discontinuous part I of this book), Jensen foots the bill in a mere 984 pages, which, although placing it somewhere on par with War and Peace, nonetheless forms a tight, if unusually bulky critique of this 3,000-year institution. Altogether or taken separately, the two books provide one hell of a tour I highly recommend. Jensen's authenticity bleeds off the page. Perhaps the best, that is most relevant, book I have ever read.
http://www.amazon.com/exec/obidos/ASIN/1931498571/qid=1103575571/sr=2-3/ref=pd_ka_b_2_3/103-1776237-7909417