No civilisation can possibly survive to an interstellar spacefaring phase unless it limits numbers. Any society with a marked population explosion will be forced to devote all its energies and technological skills to feeding and caring for the population on its home planet. This is a very powerful conclusion and is in no way based on the idiosyncrasies of a particular civilisation… any civilisation that engages in serious interstellar exploration and colonisation must have exercised zero population growth or
