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society: make the sexual-transmission model rigorous (E9 epistasis, E10 directed sex)

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Deepen the sexual-reproduction frame before entering the full society, on
the two facets GG chose: landscape robustness and directed recombination.
Adds a Kauffman NK landscape (genotype.nk_fitness, tunable ruggedness),
finite n-parent crossover (genotype.crossover, per-gap recombination rate),
and hill-climb (parents = local optima = trained models).

E9 (recomb_landscape) -- the "why sex?" test: E8's dramatic super-parent
result used an ADDITIVE landscape. On rugged/epistatic landscapes, blindly
recombining local optima causes OUTBREEDING DEPRESSION -- offspring fall
below the parents, worse with both ruggedness and recombination rate (K=8,
free recomb: ~ -0.23), and the optimal recombination rate shrinks as
ruggedness grows. Design rule: merge freely when skills are complementary/
additive; sparingly (and with selection) when entangled.

E10 (directed_sex) -- directed sex beats biological sex: biology is stuck
with 2 random-mating parents and no offspring preview; an AI can choose
complementary mates, evaluate many recombinant offspring, keep the fittest,
and use unbounded parents (iterated recombine-then-select). Random
("biological") sex craters with ruggedness (0.66->0.51); directed sex
tracks/exceeds the best parent at every ruggedness -- converting the
outbreeding-depression catastrophe into a win. No biological analog.

Complete sexual-transmission picture: dramatic super-parent offspring when
skills are complementary (E8); outbreeding-depression risk when entangled
(E9); directed sex resolves the risk (E10). configs/layer1/{E9,E10}.yaml,
figures/plot_{E9,E10}.py, READMEs, +5 tests (117 green).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
Giorgio Gilestro 2026-07-05 11:13:37 +01:00
parent 62c68d6c8c
commit 48181a1c84
21 changed files with 614 additions and 5 deletions
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@ -281,6 +281,21 @@ C3 vertical claim deferred.*
evolution-of-sex theory; beyond Riis's single-locus n-grams. `tests/test_genotype.py` (+7).
Experiment dispatch (`kind` in {genotype_lineage, society}) + `make layer1` wired.
**2026-07-05 — sexual-transmission model made rigorous (E9/E10): landscape robustness + directed sex.**
- GG excited by the sexual metaphor; wanted it robust before the full society. Added NK landscape
(`genotype.nk_fitness`), finite n-parent `crossover`, `hill_climb` (parents = local optima).
- **E9 (`recomb_landscape`) — "why sex?":** on rugged/epistatic landscapes, blind recombination →
**outbreeding depression** (offspring below parents, worse with ruggedness + recombination rate);
the optimal recombination rate shrinks with ruggedness. Design rule: merge freely when
complementary, sparingly + selectively when entangled.
- **E10 (`directed_sex`) — AI beats biology:** random ("biological") sex craters with ruggedness
(0.66→0.51); **directed sex** (choose mates + select offspring + unbounded parents, iterated) tracks/
exceeds the best parent at every ruggedness. The distinctly-AI superpower, no biological analog.
- Complete picture: dramatic super-parent offspring when complementary (E8); outbreeding-depression
risk when entangled (E9); directed sex resolves it (E10). `configs/layer1/{E9,E10}.yaml`,
`plot_{E9,E10}.py`, READMEs, +5 tests (117 green).
## Remaining (all optional / next)
- [ ] **The dynamic society:** an evolving *population of parents* (specialists) that ground +