How do you think the earth could support 15 billion hunter gatherer humans? Would that not require an enormous amount of arable space?
Rather I meant a (energy) consumption per capita that was similar to hunter gatherers. ie. people only lived to eat, have shelter and survive.
That we can support.
Everyone having cars, eating beef 7 days a week, massive amounts of waste and all the amenities that a median person in a developed country enjoys.....those things are out of reach.