Let’s get these two arguments out of the way:
Our current ecological predicament defies all common sense. How did we get here? Following are two common assertions:
1) “Humans are an inherently flawed species: greedy and destructive.”
2) “Humans reproduce too much and thus we have to develop expansionist lifestyles and complex infrastructure to support our growing numbers.”
The problem with both explanations is that they’re incorrect.
1) We are not inherently greedy. Human nature is social and tends toward cooperation and collectivity (evolution in small, nomadic bands selects for empathy), and highly adaptable to circumstances. For nearly the whole of our species’ 200,000-year existence, humans lived sustainably. Some hunter/forager societies still exist, and they manage to avoid killing their landbases. It’s only within the last 6,000-10,000 years, roughly corresponding to agriculture and the rise of class-divided social formations, that individualism and greed have been rewarded, and human activity has such a destructive effect.
2) The global human population grew very slowly until it exploded during the Industrial Revolution (and, in particular, as a result of the so-called “Green Revolution” of industrial agriculture). The distribution of social agents is determined by structural places. Our numbers grew to fill the needs of the economy for workers, consumers, and a reserve army of labor; not the other way around.