Origins of Life on Earth - Biology Online
"It is believed that heterotrophs were the first beginnings of life on Earth, inhabiting the sea and absorbing the organic material that was being created by the reactions of Earth at the time (i.e. the creation of amino acids). The building blocks of life created these organisms and also acted as a food source."
I learned in biology last year that the creation of the first amino acids had something to do with lightning hitting some particles, but I'll be damned if I can't remember what the actual experiment to test that theory was (toretorden, any ideas?). Point is, amino acids were pretty lucky, but this planet's perfect conditions is the real fluke.