indirect encoding

How do biological organisms grow their nerve systems?

Neural circutry is grown through a developmental process.
Each cell contains the same developmental program.

Indirect encodings:
$\text{encoding}:\text{genotype}\to \text{phenotype}$
Developmental indirect encodings:
$\text{encoding}(t):\text{genotype}\to \text{phenotype}$
→ Can’t arrive at the phenotype in a single time-step, but unfold it through a series of time-steps.
Conjectured to be analogous to computational irreducibility in some CA rules.

What’s interesting about indirect encodings?
compression: size of genotype << size of phenotype (1GB << 700TB)
generalization: genomic bottleneck hypothesis (incentivized to learn adaptive behaviors)