Hemenway says resilience is the main feature of the next pair of design features of permaculture. Here is his point 5:
"Work with edges. That is where the action is. Straight lines have far less edge than waves. You know this instinctively. People gravitate to the edges, like a beach, the forest edge, the side of the path, or the living room wall (where we put our furniture).
Nature amplifies edges, as in your lungs or kidneys, when it wants to amplify energy transfer; it reduces surface edges, as in a dewdrop or a turtle shell, when it wants to limit transactions. There appears to be no limit to the extent that knowledge and awareness of edge effects can improve on a design. Study of edges in nature willimprove our understanding and ability to use this principle."
"Encourage diversity. Diversity here is intended to be diversity of relations between things, and not just a bunch of different structures assembled. A garden with an assortment of different plants randomly arranged will not be nearly as productive as one in which the plants are arranged as co-productive companions.
Designed diversity is a concept I find difficult to discuss separately from its intimate relationship to redundancy and edge effects. Diversity of pathways is redundancy. Diversity allows both stacking and repeating of function."
This is Angevine:
"The human nervous system is a hierarchy, culminating in the brain, of 100 billion or more neurons of 10,000 types, 1-10 trillion neuroglial cells, 100 trillion chemical synapses, 160,000 kn of neuronal processes, thousands of neuronal clusters and fibers tracts, hundreds of functional regions, dozens of functional subsystems, 7 central regions, and 3 main divisions. All of these parts form a coherent, bodily pervasive, diversified, complex epithelium with interdependent connectivity of neurons, mostly neither sensory nor motor but anatomically and functionally intermediate."
So, here we have a single epithelium (or "edge") that has permeated throughout an entire organism (which it built with a earlier kind of cell offspring), and has diversified into 10,000 types of neuronal cells. From Six Crucial Properties of Nervous Tissue, we see this:
"The nervous system is an epithelium, with cells close by and little space between. Far more complex than other epithelia, with flattened cuboidal or columnar cells in single or stratified sheets covering surfaces or lining spaces, the nervous system is a supereptithelium: a huge three-dimensional jigsaw puzzle with billions of pieces of varying size (1 to over 150 um) length (1 um to 1 meter) and, in some cases, an extraordinarily complex and beautiful configuration. Electron micrographs show that its pieces fit together, precisely and intimately, with little space left over, an evident benefit for cell communication."
Nature took this 'edge' and folded it into a roundish hemispheres.
More to come.