Embryonic Development Through a Systems Architect's Eyes

I approach embryonic development 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.

Development emerges from cell division, gene regulation, positional signals, mechanical forces, cell movement and communication among neighboring cells. A body is constructed through interacting processes rather than by cells reading an explicit three-dimensional coordinate list.

Where does state live?

Development emerges from cell division, gene regulation, positional signals, mechanical forces, cell movement and communication among neighboring cells. A body is constructed through interacting processes rather than by cells reading an explicit three-dimensional coordinate list.

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?

A systems architect sees a distributed coordination problem: local agents respond to local state while a reproducible large-scale form emerges.

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?

A deployment plan starts with an externally specified target. Development helps create both the structure and many of the conditions that guide subsequent steps; execution and construction of the 'plan' are inseparable.

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

Experimental embryology, reaction-diffusion models and modern regulatory biology progressively replaced simple blueprint pictures with dynamic models of pattern formation.

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.

Development asks how global form can arise when no individual cell contains a complete map of the organism.

Where is the body plan if no cell possesses the complete body?

Reading trail

• Quanta — The Math That Tells Cells What They Are
• Aeon — The cell is not a factory
• Aeon — We are not machines

These links are starting points for the scientific and historical ideas. The systems interpretation, analogies and conclusions here are my own.