Life has existed on this planet for billions of years. Most of it, BTW, is still bacteria. Within the last century, give or take a couple of decades, a single species which has existed for almost no time at all has managed to construct automobiles, iPods and atom bombs and in the process push the planet closer and closer to a point where it cannot support the civilization which makes iPods sellable - and we've had the chance to do that only because the creatures who were successful here for hundreds of millions of years got in the way of an asteroid. Huh. It's entirely possible - plausible, in fact - that the Universe is teeming with life and that almost none of it has learned the use of fire.