It's not clear what you're trying to say. All human colonization to date has been dependent upon fertile lands or extensive outside support. If we want to colon

It's not clear what you're trying to say. All human colonization to date has been dependent upon fertile lands or extensive outside support. If we want to colonize Mars, we should prove we can survive without these things, and since nobody has done that on Earth, why should anybody they think it can be done on another planet?