The Buddhists and Hindus thought of this thousands of years ago, but they went into much greater depth and came to the realization that humans (and anything else) can't live (exist) without anything else. It is perfectly OK to say that the universe (and you) depends on just a single grain of sand (and vice versa).

See:

https://secure.wikimedia.org/wikipedia/en/wiki/Prat%C4%ABtya...

Though the wiki doesn't do a very good job discussing the topic. See also the section there "Madhyamaka and Pratityasamutpada" which goes a bit further in depth, but I recommend outside reading as well if you're interested.

What's interesting about this, is that when you put it that way some people are put off and call it "mysticism", when actually it is very precise and scientific, and in fact is simply another way of stating the First Law of thermodynamics.