Douglas Adams had a better analogy - he said fittest is just best fit. A puddle of water looks around itself and sees that the ground beneath it fits it perfectly - so it concludes "This ground was designed for me - there must be a designer!" Of course it is the water that fits to the ground - it morphs itself to fill the hole perfectly. Life evolves to fit the planet like water morphs to fit an impression. So the word fittest seems to work better in that sense of the word fit. But further analysis might expose this again to be as tautologically true.