ABSTRACT
One way to classify biological mechanisms is according to the objectives pursued whether they are aimed at sustaining an organism, or at an organism’s growth and development. Once nature had introduced such phenomenon as development and its steadfast companion change, the hierarchy of the various mechanisms of biological dynamics had shifted dramatically. Division-based reproduction makes somatic cells the only source of change. Under germ-cell reproduction, two mechanisms of change are possible: a joint germ/somatic cell mechanism and germ-cell mechanisms only. Some hypothetical examples of the growing developmental complexity of living creatures should clarify the link between these two mechanisms. As far as the sources of change are concerned, in single-cell organisms the somatic and the germ mechanisms of change are one. Imagine a two-cell organism. Each cell is a microcosm, in the sense of being able to divide and produce a new organism.
