At the risk of changing some of their ideas, what follows is my own synthesis of the chapter with a few quotations thrown because they say it better than I could. The human brain is a truly extraordinary instrument. All earlier life has been utterly ignorant of these things. In terms of evolutionary thought, is being smart an overspecialization which will ultimately drive us to extinction. Or will something else.
Extinction is a part of life.
Two million years from now most of the species that now exist, will be gone. We could be. After all, the dinosaurs populated the earth for over 160 million years. However, recent research has shown that mass extinctions do take place once in a while and seem to take place at fairly regular intervals. One can envision natural mechanisms for extinction such as extreme volcanism that cruds up the atmosphere shutting out the sunlight.