Modularity and Incremental Change

Survival, whether as members of the human species or as professionals in a clinical, research, or commercial environment, depends on the ability to adapt. 

Biological systems are modular. There are a few fairly simple building blocks that are used for multiple purposes, and it is the adaptation of these building blocks for new purposes that makes 

Challenged with antibiotics, microbes evolve to new forms capable of immunity. Challenged with insecticides, insect pests evolve to become immune. Adaptation of weeds under herbicide pressure also occurs. In each case, entirely new organisms were not created. Rather, there was an adaptation of existing parts, put together in new ways. 

We have become so accustomed to this tendency that we have lost appreciation for the fact that unique functions can be achieved by existing forms assembled in new ways. Thus, each cell in early fetal development can become nerve, bone, or liver further modification fixes their functions. 

New genes, new organs, new species, and new family members do not appear spontaneously, but are derived from existing genes, organs, species, and family members. The differences are sometimes larger and sometimes smaller, but they are clearly related. 

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