Perspectives
Natural Selection Through a Systems Architect's Eyes
Engineering optimization offers language for constraints, trade-offs and local improvements. Selection can resemble a blind local search using whatever variation…
I approach natural selection with an occupational habit: I want to draw boxes and arrows. That habit is useful because architecture forces questions about state, boundaries, interfaces, resources and failure. It is dangerous because natural systems were not designed to respect our diagrams.
Natural selection occurs when heritable differences affect reproductive success in a particular environment. It can make some traits more common without inspecting all possibilities or guaranteeing a global optimum.
Where does state live?
Natural selection occurs when heritable differences affect reproductive success in a particular environment. It can make some traits more common without inspecting all possibilities or guaranteeing a global optimum.
Software gives us the expectation that important state should have an owner. Natural systems often distribute state across structure, concentrations, relationships and history. A snapshot can therefore tell us less than the process that produced it.
Where are the interfaces?
Engineering optimization offers language for constraints, trade-offs and local improvements. Selection can resemble a blind local search using whatever variation exists.
Engineered interfaces are declarations. Natural boundaries are often material: membranes, tissues, ecological borders, channels, gradients or social conventions. They can leak, adapt and participate in the behavior they constrain.
What is the failure model?
An optimizer normally has an explicit objective function. Organisms face multiple changing pressures, and evolution includes drift and migration as well as selection.
Failure analysis is useful because normal operation hides assumptions. A healthy component can coexist with an unhealthy whole. A local optimization can damage the larger system. Robustness at one level can create fragility at another.
History is part of the architecture
Darwin and Wallace independently recognized natural selection as a mechanism capable of explaining adaptation; population genetics later made the process mathematically precise.
In a designed system, legacy structure may be accidental baggage. In an evolved or historically accumulated system, legacy structure can be the reason the current architecture exists at all. The path is not documentation around the system; sometimes it is part of the system.
The zoom test
A good architectural description should survive zooming. Going down a level should reveal mechanisms capable of implementing the higher-level pattern. Going up should reveal regularities that justify discussing the larger entity in its own vocabulary.
Natural selection is striking because it can produce apparent purpose without anticipation.
How much apparent design can emerge from a process that never sees the final result?
Reading trail
These links are starting points for the scientific and historical ideas. The systems interpretation, analogies and conclusions here are my own.