Why should anybody start looking for intellegent life here on earth? Lets be honest sometimes we have difficulty finding intellegent life here ourselves, however on a more serious note though, would it be easy to find us if someone out in the universe at large was looking to find life?
Is carbon and water based life forms the only type that is possible? Out of all the billions of suns in the universe how can we say that...
It could be that many years ago they managed to destroy thier own planet and have been forced to become subsurface dwellers just to survive. Living on self made food stuffs and using thier technology to survive. There is also the other probability, maybe they are still living in the prehistoric era, going out dinosaur hunting.
It is a very funny fact that mankind is always the most advanced thing ever thought of until somebody mentions ET's then all of a sudden we are so many millions of years behind them that thier technology would make them look like magicians. Imagine a stone age man who has just spent ten minutes banging two rocks together to light a fire seeing a man who can by moving his thumb cause fire to spring from his palm. This man would be seen as a god and not just a person holding a cigarette lighter.
Is it not possible that we are more advanced than any alien cultures in the near vacinity. Whilst I am not saying that this is the case I am just showing the other side of the coin
All this just goes to show that aliens could have very different ideas of where and what to start looking for, assuming of cause that they believe that "they are not alone!"