there are already more of us than we know how to sustain

what is the evidence for that? if that were true then we would have lot's of people going hungry, but that's simply not the case. poverty is getting reduced world wide. if we could not sustain the current population, we should have lots of people dying from hunger and the population should stop growing. but the reason why population is growing especially in africa is exactly because the growth is still sustainable. if it wasn't, then it could not be growing.