Alt text: They're up there with coral islands, lightning, and caterpillars turning into butterflies.
This is rather as if you imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in — an interesting hole I find myself in — fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!' -Douglas Adams
Lines up perfectly ... for life as we know it. See also: The Anthropic Principle