ABSTRACT
This chapter describes the time scales of biological phenomena from a number of different perspectives. In the moment-to-moment life of the cell, proteins do most of the work. Many proteins are able to operate at time scales much faster than the relatively stately machinery carrying out the central dogma operations. The general rule that all biological processes are dynamic and undergo change over time applies to molecules, cells, organisms, and species. The evolutionary clock started more than 3 billion years ago with the appearance of the first cellular life forms on Earth. It is unsatisfying to rely on the extrapolation of mutation rates measured in artificial laboratory experiments to the evolution of species over time in the real world. Real-world conditions are much less stable or controlled than laboratory conditions, and furthermore the time scales of greatest interest for studying the evolution of species are much longer than can be achieved in the laboratory by even the most patient experimentalist.
