I remember seeing on television an anthropological program which pointed out that one of our forebear species used stone tools for a million years without advancement. But that means they survived for a million years. For the sake of discussion, I assume that that one million year period ended about one million years ago. Then that's two million years from the first use of stone tools to the present. I arbitrarily assigned a value of one economic unit to that first use of stone tools, and I estimated what we have now to be one thousand trillion economic units. (I saved a clipping from the 28-29 March 2009 edition of Australia's national newspaper which estimated the global economy to have a value of sixty trillion US dollars. That would make the stone tool economic starter unit equal to about six US cents in March 2009 value.) I asked myself what sustained annual growth rate would change one into a thousand trillions in two million years. The answer I calculated was less than two tenths of a basis point. I believe this says something important about the sustainability of perpetual growth, which is the clear de facto definition of success in today's economies - local, and national, and global. The details of my calculation and argument are here.