For all space buffs and such, 

Now I know this is going to sound strange, but why follow the water. Just because life on Earth requires water does that make for a universal "theme"?  Heat and water are not known to be the universal keys to life.  There is so much to learn beyond Earth.   Carbon based life is only one.  As has been coined before, Look outside the box.  We think of life in a very narrow, contained format.  Even in that contained format Polar Bears and deep sea oraganisms are quite different than than the human race.  We are only looking at a global theme, outside the box requires a more universal theme.  The ground to us is rock,  dust and dirt.  The ground on Saturn, Jupiter and other gas giants it is  gas.   Who ever decided that breathable air has to be oxygen?  Sure thats how it is on Earth,  might oxygen be a poison to other life forms?  Think outside the box.  Humanoid?  Here is another narrow view.  Just because we are does not make it universal,  Mankind is quite vain.