Decay and death are an inevitable consequence of the world that we live in. The forces of entropy wage a slow but implacable battle of erosion on everything. The major discovery made by the earliest cells, which allows life in our world of entropy, is the ability to maintain order when challenged by this inevitable decay into equilibrium. We might imagine two ways to face this great challenge: immortality or planned obsolescence. An immortal organism would be completely resistant to environmental forces, or have powerful repair mechanisms to undo damage as it occurs. This obviously was too much to ask for the earliest cells, which were built from fragile organic materials. Instead, they developed along a path of planned obsolescence (Fig. 7.1). Molecules, cells, and organisms are all born perfect and new, they live for a minute, a year, or a century, and then they die…but not before reproducing to create a new molecule, cell, or organism.