You posted: " Actually, I have to disagree. The human species has always had an equilibrium population, with little variance(this is verified in genetic markers). In the past three million years, we have survived three separate geological disasters, including ice ages, which diminished populations to tens-of-millions, after which we always rose back to 6 billion. It's our magical number. The baby boom after WWII was a rather small fluctuation by comparison and is only temporary (baby boomers are already on their way out). The thing that is clear out of all of this is that our consumption and waste has gone up million-fold per capita, and increases daily. We need to embrace the "waste not, want not" philosophy"
Am I misreading your post, that prior to the ice ages, the pop of the earth was 6 billion and we are returning to that pop today?
While you are correct that consumption and waste are out of control, until recently, the pop of earth has never exceeded a billion. Only in the past couple of thousand years has it exceeded a couple hundred thousand.
There is no possible metric of sustainability that would allow earth's pop to stabilize at 6 billion. Looking at all metrics, and choosing the smallest sustainable pop from those metrics would probably be far less than a half billion, although no one I know as conducted such an extensive calculation although it is high time one was done.