Sequencing of genomes did not reveal the "secret of life" and left biologists and philosophers unsatisfied. It became clear that post-genetic, epigenetic (taken in a wide sense, post-translational) events play an important role even during development and adult homeostasis. Such mechanisms become predominant during aging, and explain the differential decline of functions (aging in "spare-parts"). Some of these post-translational mechanisms, leading to auto-amplifying vicious circles, will be described.