What metaphors are used in The Story of B by Daniel Quinn?

In Section 12, B's second lecture, he draws a parallel between a frog and Man as he provides a metaphor of a frog allowing itself to be boiled to death if one puts the frog in warm water and gradually increases the temperature. B compares this to how Man was placed into warm water during the Agricultural Revolution, and during the next 10,000 years, Man demonstrated signs of distress in the form of war, crime, civil revolt, slavery, the advent of revealed religions, the advent of Salvationist religions, the bubonic plague, the Inquisition, diseases, world wars and economic collapse. He claims that these are all reactions to overcrowding in the world.
Finally, B ends this lecture by stating that at the present time, the frog is already dead, and the only thing that remains is cultural collapse.