I have to disagree with xkcd a little bit.
The problem is with not learning enough about biology. Once you know enough, you appreciate that the whole of your existence is wallowing in a cloud of everything and you might as well accept it — we’re all interconnected and part of the whole. Then, once you know too much, you find yourself wondering if your wife would mind if we invited a swarm of spiders to join us for a dinner date.
I made a graph.