In fact, every organism expands to the limits of the resources and competition. Living on the edge of starvation is the default condition.
In fact, only until the agricultural revolution was this ever any other way. This enabled a massive population increase. The second occurrence was the industrial revolution, which yielded another massive population increase from which the world is still undergoing.
The former yielded the first kings, etc, because it permitted a small fraction of the population to live above subsistence. The industrial revolution and modern economics (capitalism) was the first time in the existence of any population that large fractions of a species lived in a state better than that.
Agriculture, from the point of view of human diet, was a huge compromise, it now seems, if you follow the Paleo movement. We started evolving maybe 2 million years ago, and in all that time we grew to become adapted to hunting and some gathering, but essentially, we are very fit for sweaty long distance running, and with some tracking, can eventually run other big animals to death. But then we invented agriculture, which was only 10 or 12 thousand years ago. Then with modern farming we changed the nature of the stuff we were growing even further. And all this is taken as a *hint* that we are not adapted to modern diets largely comprised of industrially grown grains and sugars. Those paleo ancestors didn't have to carb load to run the distances they did, their bodies were adapted to run on fat stores, and modern athletes are starting to experiment with this and discover that yeah, you really can burn better on fat. So then, was agriculture a huge mistake?
Well, it got us here, it allowed our populations to grow, allowed more people to live together, and as you say, have Kings and later Parliaments, and so the whole social structure adapted and evolved to the need to integrate ever larger numbers. Empires worked for thousands of years but they eventually crumbled under the sheer weight of their own expansive and "too hard to administer" centralised control.
So we eventually created the "individual" and say that the individual should have more power to make local decisions, and so you have the notion that, in a modern economy, the brain power is more distributed, and so can process more variables, more local differences, and so the system still manages to work, when an empire would have crumbled already.
So that brings me to the point of this, and that is, agriculture and industrialisation, Empires and Democracies, have got us this far, but what is next?
The world is still developing, but many of the cultures are still recoiling at globalisation and development. People compare humanity to a petri dish and imagine that we will at some point reach the edge of the dish, and having consumed everything, collapse. Because, you know, humans have the brain power of an amoeba.
I think what is closer to the truth is that we have always and always shall be faced with the problem of survival. We faced it when we were hunter gatherers, we faced it when we were dying of the plague in medieval Europe, we faced it again and again and always shall face it. We are living biological machines in an environment which is nicely-called "Nature" but nature is a bitch.
So the question is how to survive, and a fashionable answer is that we should stop consuming. Well, that's like trying to breathe more slowly when you are trapped in a hole with limited air. Sure... that'll buy you some time, but that is not sustainable. The real answers are about inventing a way to get out of the hole.
As humans we have imagination and creativity and reason and intuition, and "sustainability" means inventing a heck of a lot of new stuff, yes, stuff, which will then make life easier for everyone. The natural birth rate for people, women if their children survive, is 2 children per couple. We don't overpopulate because we have too much stuff, we overpopulate because we have too little stuff and it is a desperate survival strategy. Having more stuff allows us to ease back and stop popping out babies and wearing out women's bodies. Do people think women want to have six children?
But we are in a transition period, still, and still paying the price in our health, for the compromise of agriculture, as did all those Egyptians who had awful tooth decay from eating grains. But the answer isn't to just stop eating, stop consuming, stop living. We have to continue to invent new and better stuff, and lots of it.
Fortunately most of the world will continue to do that even if it has become fashionable in the West to get all down about progress (thanks Romantics! thanks Derrida!)
So I imagine or hope that one day, every human on the planet will live in a humanistically informed culture, have plenty of time to devote themselves to whatever interests them, and have a lot of control over their own lives, and have resources to support that, and the technology will have reduced dependence on the leviathan state, and people's ethics will have evolved to live globally and peacefully. And it'll be powered by a lot more energy than we use now. A *lot* more.