Perspectives
Where the deployment plan Analogy Breaks
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…
Calling embryonic development a deployment plan is useful for about five minutes. The comparison can expose structure that ordinary language hides. The problem begins when the comparison stops behaving like a tool and starts behaving like a claim about what the thing literally is.
A systems architect sees a distributed coordination problem: local agents respond to local state while a reproducible large-scale form emerges.
What the metaphor gets right
A systems architect sees a distributed coordination problem: local agents respond to local state while a reproducible large-scale form emerges.
This is why engineering metaphors are so attractive. They compress a complicated relationship into something we can manipulate mentally. In the best case, the metaphor produces predictions and sharper questions.
What it smuggles in
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.
Engineering words often carry hidden assumptions: a designer, a specification, modular ownership, explicit goals, a stable machine underneath the program. Those assumptions must be tested rather than inherited.
Return to the physical story
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.
Once the mechanism is back in view, the analogy can be kept on a short leash. We can state which relation is genuinely similar and which difference would make the analogy generate a wrong prediction.
My three tests for a metaphor
- What mechanism does this comparison help me see?
- Which engineering assumption does the natural system not share?
- What would I predict incorrectly if I took the comparison literally?
The third test is the most important. An analogy that cannot fail is decoration, not explanation.
Beyond the borrowed language
Experimental embryology, reaction-diffusion models and modern regulatory biology progressively replaced simple blueprint pictures with dynamic models of pattern formation.
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?
A good metaphor should eventually make itself less necessary. It gets us close enough to the real system that we can see where the scaffolding ends.
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.