Part VII: Empirical Program

The Substrate Ladder

The Substrate Ladder

V13 replaced learned attention with a simpler mechanism: content-based coupling. Cells interact more strongly with cells that share state-features — a form of chemical affinity rather than cognitive attention. Three seeds, thirty cycles each, evolving on GPU with lethal resource dynamics and population rescue.

Mean robustness: 0.923. But at population bottlenecks — moments when drought kills all but a handful of patterns — robustness crosses 1.0. The survivors are not merely resilient; they are more integrated under stress than at baseline. This is the biological signature, appearing for the first time in a fully uncontaminated substrate.

From V13 we built upward, adding capabilities one layer at a time:

  • V14 (Chemotaxis): Motor channels enabling directed foraging. Patterns move toward resources rather than passively waiting. Comparable robustness.
  • V15 (Temporal memory): Exponential-moving-average channels storing slow statistics of the pattern's history. Oscillating resource patches reward anticipation. Evolution selected for longer memory in 2/3 seeds — the first clear evidence that temporal integration is fitness-relevant. Under bottleneck pressure, Φ\intinfo stress response doubled.
  • V16 (Hebbian plasticity): Negative result. Mean robustness dropped to 0.892 (lowest of V13+). Plasticity added noise faster than selection could filter it.
  • V17 (Quorum signaling): Highest-ever single-cycle robustness (1.125). But 2/3 seeds evolved to suppress signaling entirely.
  • V18 (Boundary-dependent dynamics): An insulation field computed from pattern morphology creates distinct boundary and interior signal domains. Boundary cells receive external convolution; interior cells receive only local recurrence. Three seeds evolved three different membrane strategies — permeable, thick-insulated, and filamentous. Mean robustness: 0.969, the highest of any substrate. Peak: 1.651. But internal gain evolved down in all three seeds. Evolution preferred thin, porous membranes over thick insulated cores.

The substrate ladder taught two lessons. First: the only addition evolution consistently selected for was temporal memory. Plasticity, signaling, and boundary complexity were either suppressed or reduced. Second: raw robustness kept climbing (V13: 0.923, V15: 0.907, V18: 0.969), but this did not translate into richer cognitive dynamics. Making patterns more resilient is not the same as making them more minded.