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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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configs/layer1/E9.yaml Normal file
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experiment: E9
kind: recomb_landscape
seed: 20260705
n_replicates: 24
# (Landscape robustness / the "why sex?" question — the credibility centerpiece): E8 showed sex wins
# on an ADDITIVE landscape, where recombination trivially helps. Does it survive EPISTASIS? Parents
# are local optima ("trained models") of a Kauffman NK landscape whose ruggedness K (epistatic
# interactions per locus) is swept with the recombination rate. Expect: on smooth/mildly-rugged
# landscapes recombination helps; on rugged ones FREE recombination (rate~0.5) breaks co-adapted
# blocks and offspring fall BELOW the parents (outbreeding depression); and the OPTIMAL recombination
# rate shrinks as ruggedness grows. Design rule: merge freely when skills are complementary/additive;
# merge sparingly when entangled. Falsifier: recombination rate has no effect, or free recombination
# never underperforms the parents on rugged landscapes.
society:
L: 12
n_parents: 6 # trained specialists = local optima of the landscape
pop: 200 # recombinant offspring sampled per (K, rate, replicate)
sweep:
- param: K
values: [0, 2, 4, 6, 8] # landscape ruggedness (epistasis): 0 = additive, high = rugged
- param: rate
values: [0.0, 0.05, 0.1, 0.2, 0.35, 0.5] # clonal -> free recombination
output: {dir: results/E9}