I like the concept of the Anthropocene. It finesses or postpones at least some of the conflict around the idea of climate change, broadens the conversation to include all human impact on the environment, and grounds thinking in geological (heh!) time without overloading it with burdensome sentiments like guilt or fear. The term leaves the future open to both positive and negative possibilities. It acknowledges human agency as the most powerful force currently reshaping the planet without getting too judgmental about what that means.
I find existing definitions of the Anthropocene unsatisfying though. Most of them, reasonably enough, focus on planet-scale external markers, ranging from the birth of agriculture to the first nuclear tests and climate change. But this seems too open narrative arbitrariness and not open enough to insight. If we turn inward though, there is a rather natural and fertile definition that immediately suggests itself:
The Anthropocene begins when survival in the built environment is as cognitively demanding as survival in the natural environment of evolutionary adaptation.
Note that “as cognitively demanding” is not the same thing as “as hard across the board”. It means you you have to think as hard for the same survival probability, but many other things might get easier.
A good illustration of this is life in a major city versus life in a small town. The former is more cognitively demanding but many things besides thinking become a lot easier. Nobody ever moved to a bigger city in search of a simpler life. A less emotionally stressful life, perhaps. A less impoverished life, perhaps. A more comfortable and convenient life, perhaps. But not a simpler one.
Now let’s apply that reasoning at civilizational history scale.