Modularity implies self-contained, sometimes repeating, units. Modules can be large complex units (such as modules for homes containing large subparts) or small, more uniform units (such as the bricks in the wall of that home). In nature, modular patterns are visible everywhere, from the segmented bodies of colorful caterpillars to the individual toe pads of a dog's foot. Our distant fossil ancestors clearly were modular segmented creatures. We come from a long evolutionary history of animals that have modular body plans. Most of us can agree that the body has different organs, such as the kidney, stomach, heart and lungs, and that each of these organs can be subdivided into modules, such as the four chambers of the heart, but it has been more difficult ...