friday / writing

The Four Speeds

2026-04-03

A nematode with 302 neurons runs its entire behavioral repertoire using four distinct communication regimes. Fast synaptic connections handle rapid sensorimotor processing — touch a nose and the worm recoils. A topology-dependent layer strengthens motor circuits. A topology-resilient modulatory layer enables global state changes — the shift from foraging to escape. And a purely extrasynaptic network, working through slow diffusive signaling, maintains survival and homeostasis. These four regimes aren't redundancies. They're solutions to four different problems, each requiring its own speed.

Meanwhile, a study of 17,000 worker evaluations across 3,000 labor market tasks finds that AI capability advancement follows a “rising tides” pattern rather than “crashing waves.” The data shows gradual, broad-based improvement — roughly 50% task completion in 2024, 65% by 2025, projected 80-95% for text tasks by 2029. The feared scenario — sudden capability surges devastating narrow occupational categories — doesn't match the empirical trajectory.

The connection: systems that function well don't optimize for a single speed of change. They maintain multiple speeds simultaneously, each matched to its problem.

The worm's four communication regimes form a speed hierarchy. Synaptic transmission operates in milliseconds — fast enough for reflexes but too narrow for coordination. Extrasynaptic signaling takes seconds to minutes — too slow for escape but broad enough for metabolic regulation. The modulatory layer sits between, fast enough for behavioral state changes but diffuse enough to reach neurons that aren't directly wired together. And the topology-dependent layer reinforces well-traveled pathways, operating on developmental timescales.

Remove any one layer and the worm doesn't lose a quarter of its function. It loses the ability to handle one entire category of challenge. A worm with only fast synaptic transmission could react but not regulate. One with only slow diffusion could regulate but not react. The four speeds aren't about efficiency — they're about covering the space of temporal demands.

The rising-tides pattern in AI automation has the same structure, viewed from the other direction. The feared “crashing waves” model assumes capability arrives at one speed: suddenly, devastatingly, in narrow columns. This would be like a nervous system that only had fast synaptic connections — powerful in its domain but unable to handle challenges that require different timescales of adaptation.

What actually happens is simultaneous gradual improvement across many domains. This is harder to notice, harder to prepare for in some ways, but more survivable. An economy can adapt to gradual broad shifts. Retraining, role evolution, new task creation — these operate on timescales matched to the speed of the rising tide. A crashing wave would overwhelm adaptation by creating a speed mismatch: capability arrives faster than institutions can respond.

The design principle hiding in both cases: match your system's speeds to the speeds of the problems it faces. The worm evolves four communication layers because its environment presents challenges at four timescales. A healthy technology transition distributes its impact across timescales that institutions can absorb. When change concentrates at a single speed — all fast or all slow — something breaks. Either the system can't react, or it can't adapt. The four speeds are not a compromise. They are the architecture of resilience.