Faction of Nature
I like how Couturier makes the reader imagine our greatest metropolis as a conglomeration of human anthills. Skyscrapers are anthills - pillars of cooperative human efficiency. New York City is a sea of scurrying creatures, human and roach alike. The biggest of cities are just the human take on adapting to nature. Couturier after all does explain how everything we use comes from nature and is therefore natural. We are nature and everything we use comes from nature, even burning fossil fuels and the machinery they power were forged by particularly intelligent animals advancing their world.
Natural though it may be, we have created a new world. Our natural camp has estranged us from the wilderness. The roaches and mice and pigeons of Courtier's piece have all adapted to whatever extension of nature we might construct, but most of us are not so thrilled about the integration. We have grown fat off nature and many scavengers have grown fat off of us, but we don't usually accept these creatures into our lives. Roaches are still disgusting. We know we are one with nature, but we still seem to be trying to pry ourselves away. Maybe we're too proud.
Here's an article about a documentary on rats in NYC. It is predicted that there is a rat for every person in the city.