paper: expand results summary to the full study
Rename layer1-summary.md -> results-summary.md and rewrite to cover the whole body of work with the sexual-reproduction arc as the through-line: Layer 1 (E1-E6, Wright-Fisher core + closed forms), Layer 1.5 (neural existence proof: histogram bridge, RNN metric reframing, architecture- generality, recombination in weights, real-MNIST external validity), the learning kernel (neutral drift fails both neural models oppositely), the sexual society (E7-E11: advantage of sex, Fisher-Muller super-parents, outbreeding depression, directed sex, the dynamic-society vertical claim), and the Riis positioning (concede collapse=drift; lead with the cure). Technical + accessible halves; six design rules. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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# The Lamarckian Society — Summary of results
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*The complete laptop-reproducible body of work: the analytical core (Layer 1), the
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architecture-general neural existence proof (Layer 1.5, including real MNIST), the learning
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kernel, and the sexual-reproduction society (E7–E11). Two summaries of the same work — one
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technical, one accessible.*
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**The arc in one breath.** Model collapse is **asexual, self-consuming degradation**: a lineage
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trained on its own outputs drifts to its own mode and loses the rare tail. We show this is
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*literally* a Wright–Fisher drift process (validated against closed forms), reproduce it in real
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trained neural weights and on real MNIST images, and then establish the **cure** — a **grounded
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sexual society**: reality-checking (grounding) plus **recombination across many decorrelated
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parents** (sexual reproduction, not teacher→pupil copying) plus **quality-diversity** selection.
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The payoff is not merely arrested collapse but a population whose **offspring exceed their
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parents** and whose general capability **climbs** while specialties are re-earned — and removing
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any one operator breaks it. **122 tests pass**; three of the core predictions are exact closed
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forms, so the headline curves sit on analytic targets rather than eyeballing.
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---
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## A. Technical summary
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### 1. The analytical core — collapse as Wright–Fisher drift (Layer 1)
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Knowledge is a distribution `p_t` over `K` items on the simplex; a fixed Zipf-tailed truth `p*`;
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the generational step — *sample `n` from the parent, mix in `m` fresh real samples, refit* — is
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**literally a Wright–Fisher process with immigration**, not an analogy. Each safeguard from the
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perspective paper is one operator on that step (grounding `g=m/(n+m)`; region-matched grounding;
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multi-teacher recombination; directional vs quality-diversity selection; re-minting). Because the
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process is Wright–Fisher it inherits **closed-form validation targets**, enforced as
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`<0.5%`-tolerance assertions (the "spine of trust"): neutral heterozygosity decay
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`E[H_t]=H₀(1−1/n)^t`; fixation probability = initial frequency; the *exact* mutation–drift
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equilibrium `H_eq = H*·m(2n+m−1)/(n+2nm+m²)`; the tail-persistence threshold `m·p*ᵢ ≳ 1`; and the
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recombination union coverage `U(K_T,ρ,q)=T[ρq+(1−ρ)(1−(1−q)^{K_T})]`.
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Findings **E1–E6**:
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- **E1 — collapse (null).** Neutral drift reproduces the geometric `H` decay to Monte-Carlo error;
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support collapses `K→1`; forward-KL diverges; tail *items* die ≈10× faster than head items.
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(Aggregate tail *mass* is a drift martingale — a misleading metric; tail-*item* survival is the
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honest one.)
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- **E2 — grounding phase boundary (headline).** Stationary `H` tracks the exact `H_eq`; a critical
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**`g* = 0.048` (CI [0.047, 0.050]) ≪ 1** — as little as one real sample against 200 inherited
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restores ~68% of the truth's diversity; `g=0.05` reaches 96%. The sharp threshold lives in
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discrete tail-item survival, not the smooth `H`. The **deep tail is unrescuable** by grounding at
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feasible budgets (`m* ∼ 1/p_min`) — which is what recombination is for.
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- **E3 — region-matched grounding.** At fixed budget, matched grounding holds the exercised region's
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tail (0.49) where uniform lets it collapse (0.07). Grounding protects only what it overlaps.
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- **E4 — multi-teacher recombination ("merge, don't average").** Union coverage matches the closed
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form exactly (recombination *supplies* the tail). **Principal finding:** under mean-mixture
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distillation surviving tail coverage is **flat in `K_T`** — a conservation law (averaging's `1/K_T`
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dilution exactly cancels the union gain). The benefit is realised only under a **union-preserving
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merge** (`max` over teachers, à la M2N2 model-merging). *Merge weights; don't average outputs.*
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- **E5 — QD vs greedy.** Greedy selection fixes (`H≈0.01`); quality-diversity (`w_i ∝ f_i·p_i^{−α}`)
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holds `H` at a positive plateau (0.48–0.88, rising with novelty `α`).
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- **E6 — re-minting gate.** Re-minting a *collapsed* lineage makes forward-KL to the original
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diverge (irreversible lock-in); a diversity gate (`H≥H_gate`) prevents it; healthy re-mint is
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harmless.
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### 2. Collapse in real trained weights, and on real images (Layer 1.5)
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A re-scoped, cheaper Layer 2: realise the *same* Wright–Fisher abstractions in **real trained
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generative models** on a fully-synthetic sandbox with an exact oracle, then confirm on real MNIST.
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A model's "knowledge" is its oracle-measured distribution over `K` modes; the generational step is
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*train-a-model-on-the-previous-model's-samples + grounding*.
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- **The histogram bridge (HARD GATE).** A memoryless histogram model reduces Layer 1.5 *exactly* to
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Layer 1: run through the neural runner it recovers `g* = 0.047` and sits on the exact `H_eq` curve.
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This licenses every trained-model result to be read against the analytic core.
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- **Collapse in an RNN, and the metric reframing.** A GRU retrained each generation on its own
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output drifts from truth (forward-KL climbs) and grounding arrests it — the sign confirmed. But
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the **operative neural collapse metric is forward-KL, not `H` or tail-survival**: the RNN's
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*smoothing* inductive bias keeps spurious tail modes alive, so `H` stays ~80% of `H*` and
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tail-survival is non-monotone in `g`. On forward-KL, half the divergence gap closes by a
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median-recovery grounding `g≈0.04` (echoing Layer-1's 0.048), but *full* recovery needs `g≈0.19` —
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the sharp `g*≪1` is an exact-operator feature the trained net *softens*.
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- **Architecture-generality.** Collapse + grounding-rescue appear in the **histogram, GRU, and MLP**
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alike — the operator is not an artefact of one model class.
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- **Recombination in real weights.** The E4 "merge, don't average" law reproduces: construction-level
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union rises 0.49→0.96, oracle-guided max-merge surviving coverage rises while mean-distill stays
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flat — the conservation law holds in trained weights (compressed/noisier, the expected smoothing
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caveat).
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- **Real-MNIST external validity.** A convolutional VAE (the canonical collapse vehicle) retrained on
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its own generated digits, modes = digit-class × stroke-thickness (K=30, Zipf), read by a frozen
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CNN oracle (98.5% mode accuracy, confusion matrix recorded as the noise floor): the **dry lineage
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collapses to a single mode** (forward-KL 0.5→18, support 30→1, tail wiped out, H→0), while **10%
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grounding holds all 30 modes**. The eyeball montage shows varied gen-0 digits degenerating into one
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blurry blob. Collapse and its cure are real on real images — not a synthetic artefact.
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### 3. The learning kernel — neutral drift is a null both neural models fail, oppositely
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Prompted by revisiting the neural deviations, the refit step is generalised from a pure resample to
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`p_{t+1} = T_θ(counts/n)`: a **learning kernel** with a *smoothing* knob (mutation toward a prior)
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and a *sharpening* knob (mode-competition), both identity by default (so Layer 1 is untouched).
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Result: **neutral Wright–Fisher fails both neural architectures in opposite directions.** The
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**VAE** (large `n`, small `K`): neutral drift is *inert* (no collapse), yet the real VAE collapses
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to one mode — a **sharpening** kernel reproduces it (the estimator *adds* collapse pressure). The
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**RNN**: neutral drift drives `H→0`, but the real RNN only partially collapses — a **smoothing**
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kernel reproduces the `H`-floor (the estimator *removes* collapse pressure). Model collapse in real
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learners = **neutral drift ⊕ an architecture-specific, signed estimator-bias operator**; this
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mechanistically explains the architecture-generality result and the softened neural `g*`.
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### 4. The sexual-reproduction society (E7–E11) — from teacher→pupil to sex with unbounded parents
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The single-locus, fixed-`p*` world can only express *recovery toward a ceiling*. The society's
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load-bearing claim is **vertical** — capability that *exceeds* any component — which needs
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combinatorial structure. Knowledge becomes a distribution over **genotypes** (`L` biallelic loci,
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fitness = number of correct loci), and the one new operator is **recombination**. This is where the
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frame shifts: **teacher→pupil distillation is asexual copying (caps at the ceiling); recombination
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is sexual reproduction (combinatorial, generative — offspring can exceed both parents), and unlike
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biology there is no two-parent limit.** The celebrated evolution-of-sex theory maps onto the thesis
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exactly (collapse = Muller's ratchet; merging = meiotic reassortment; "exceeding" = the
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Fisher–Muller effect):
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- **E7 — the advantage of sex.** A population adapting toward an optimum: the **sexual lineage adapts
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faster** than the asexual one (clonal interference), keeping loci in linkage equilibrium (LD→0 vs
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an LD spike). Honest scope: a *speed* advantage, not a permanent gap (the single-population ratchet
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is subtle).
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- **E8 — the vertical claim (Fisher–Muller), the headline.** Decorrelated *parents* are specialists
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(expert on their loci, agnostic elsewhere). **Sexual recombination assembles a genotype fitter than
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any parent, climbing to the optimum (12/12 — a genotype no parent had)** as parent count grows and
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correlation `ρ→0`, while the best single parent (~8.7) and the mean-mixture "model soup" (~11.6)
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plateau below.
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- **E9 — landscape robustness ("why sex?").** On rugged (epistatic, NK) landscapes, blindly
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recombining trained models causes **outbreeding depression** — offspring fall *below* the parents,
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worse the more entangled the skills and the higher the recombination rate — and the **optimal
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recombination rate shrinks as ruggedness grows**. Design rule: *merge freely when skills are
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complementary; sparingly, and with selection, when entangled.*
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- **E10 — directed sex beats biological sex (the AI superpower).** Biology is stuck with two
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random-mating parents and no offspring preview; an AI can **choose complementary mates, evaluate
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many recombinant offspring, keep the fittest, over rounds, with unbounded parents**. Random
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("biological") sex craters with ruggedness (0.66→0.51, deep outbreeding depression); **directed sex
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tracks or exceeds the best parent at every ruggedness** — a catastrophe turned into a win, with no
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biological analog.
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- **E11 — the dynamic Lamarckian society (the C3 vertical claim, realised).** A finite population of
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agents (genotypes) evolves on a rugged NK landscape that *is* reality, composing all four operators
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— grounding, directed sex, quality-diversity, mutation. Grounding is made load-bearing by the
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**consensus-conformity (self-consumption)** mechanism: selection acts on
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`g·true_fitness + (1−g)·conformity`, so at `g=0` the society optimises fitting-the-crowd rather than
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reality. A **4-arm ablation (global optimum ≈ 0.79), each breaking distinctly, only the full society
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climbing:** `full` **0.78** (climbs to the optimum, diversity maintained longest) · `no_sex` 0.77
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(can't recombine to escape local optima) · `no_diversity`/greedy 0.74 (collapses diversity fastest,
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stuck at a worse local optimum) · **`no_grounding` 0.48** (self-consumption collapse to an unfit
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consensus — trains on the crowd, regresses to a confident-but-wrong mean; the population strongly
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*agrees* while being *wrong*). The society needs **all** of grounding + directed sex + diversity: on
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a rugged landscape you need diversity to explore basins, sex to recombine them, and grounding to
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select on reality.
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### 5. Positioning — what is prior art, what is ours
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An independent 2026 paper (Riis, *Drift and selection in LLM text ecosystems*) rigorously formalises
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**collapse = Wright–Fisher drift** (martingale of minority mass, rare-first extinction, de Bruijn
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fixed points, drift+selection) with n-gram agents. **We concede that framing as prior art and cite
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it — "collapse is drift" is no longer our contribution.** Crucially, Riis's "mixed environment"
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retains the lineage's own *old synthetic* tokens (no injection of external truth), so his headline is
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*pessimistic* (extinction is independent of retention). **Our defensible contributions, ranked:**
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(1) **recombination as sexual reproduction** — the "merge, don't average" law, the Fisher–Muller
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vertical claim, directed sex, and their limits (E4, E8–E10) — an operator Riis lacks; (2) the
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**learning-kernel / estimator-bias axis**, which he *names as future work*; (3) **grounding as
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immigration from a fixed reality**, giving a critical `g*≪1` his closed loop cannot have; (4)
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**architecture-generality in real weights + real images (MNIST)**; and (5) **the integrated dynamic
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society and its vertical claim** (E11), wholly ours. The repositioning: from *"collapse is drift"*
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(diagnosis) to **a population-genetic control theory for sustaining open-ended knowledge** — the
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engineered cure and its integration.
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### Design rules that fall out
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1. **Never inherit dry, and ground where it matters** — a little reality (`g*≈5%`) protects most
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diversity, but it protects only what it overlaps, and it can't hold the deep tail.
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2. **Merge, don't average** — union-preserving model-merging realises the multi-teacher benefit;
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averaging cancels it.
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3. **Sex, with no parent limit** — recombining decorrelated specialists yields offspring that exceed
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any parent; more, complementary parents climb higher.
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4. **Match recombination to entanglement** — merge freely for complementary skills; sparingly for
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entangled ones; and *always select offspring* (directed sex), which AI can afford and biology
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cannot.
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5. **Keep diversity, and stay grounded** — greedy selection or a broken reality-signal both collapse
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the society; only grounding + sex + diversity together climb.
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6. **Gate irreversible consolidation on diversity** — re-mint a base only while the lineage is
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healthy.
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---
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## B. Accessible summary (for ML engineers and neuroscientists)
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### The question
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Modern AI is trained once and frozen because it cannot keep learning without *catastrophically
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forgetting*. The Lamarckian Society proposes an alternative: **generations** of bounded agents that
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learn, then reproduce — passing on what they learned. But there is a notorious trap: train a model on
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the previous model's outputs, generation after generation, and it suffers **model collapse** — the
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rare cases (the *tail*) vanish first and the model drifts to a bland mode. So the whole scheme lives
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or dies on one question: **when does generational transmission accumulate knowledge instead of
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degrading it?**
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### The through-line: collapse is *asexual* degradation; the cure is *sex*
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The key reframe of this work is that **teacher→pupil copying is asexual reproduction** — a pupil can,
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at best, recover what its teachers had. That caps out, and left alone it degrades (collapse). The cure
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is **sexual reproduction between agents**: combine *many decorrelated parents* so the offspring
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inherits a *combination* none of them had — and can be **better than any parent**. Unlike biology,
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AI sex has **no two-parent limit** and can *choose* mates and *select* offspring. That is the engine
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that lets a society climb instead of collapse.
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### What we found, in plain terms
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1. **Collapse is real, and it's math.** Casting generational training as the century-old
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**Wright–Fisher** drift process (not a metaphor — the same equations) gives exact formulas to
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check against. The rare stuff dies ~10× faster than the common stuff.
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2. **A little reality goes a long way — but not for everything.** Mixing in even ~5% verified real
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data restores most of the diversity and holds it (**grounding**). But the *very rarest*
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capabilities can't be saved by grounding alone — that's what recombination is for.
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3. **Collapse is real in actual neural nets, and on real images.** We reproduced it in trained RNNs,
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MLPs, and a VAE, and on **real MNIST** — where a VAE trained on its own digits collapses to a
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single blurry blob, while a little grounding keeps all the digit styles alive. (Honest nuance: real
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nets *smooth*, so "how many modes are alive" lies to you; "how far from the truth" is the honest
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ruler.)
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4. **To fight tail collapse with many teachers: merge, don't average.** Averaging their outputs
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mathematically cancels the benefit; a *merge* that keeps each item's strongest source realises it.
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5. **Sex makes offspring that beat their parents.** Recombining decorrelated specialist models
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assembles capabilities none of them had, climbing to the optimum as you add more, complementary
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parents — while averaging ("model soup") and the best single parent plateau below. This is a
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celebrated evolutionary result (the Fisher–Muller effect), now shown for AI model merging.
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6. **But sex can backfire — and AI has a fix biology lacks.** When skills are *entangled*, blindly
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merging good models produces *worse* offspring ("outbreeding depression"). The fix is **directed
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sex**: choose complementary partners, generate many merges, and keep the best — which AI can do
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and biology can't. Directed sex turns the catastrophe into a win.
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7. **The whole society climbs only with all the pieces.** In an evolving population on a rugged
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"reality" landscape, the *full* society (grounding + directed sex + diversity) climbs to the top
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while keeping its specialists; remove **grounding** and it collapses into a confident, wrong
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consensus (the exact analogue of training on the internet's AI-generated crowd); remove **sex** and
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it gets stuck; remove **diversity** and it converges too fast to a worse answer. Each failure is
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distinct; only the full society wins.
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### Why it is novel and why it matters
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- **It turns model collapse from a warning into a control theory.** Collapse-as-drift is now known
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(and independently formalised elsewhere). Our contribution is the *cure* and its integration: a
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grounded, sexually-reproducing, diversity-preserving society that not only avoids collapse but
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**climbs, with offspring exceeding parents**.
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- **The sexual-reproduction frame is, we believe, genuinely new for AI** — model merging reframed as
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meiotic recombination, with a rigorous account of when it helps (complementary skills), when it
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hurts (entangled skills), and how to make it reliably win (directed sex, unbounded parents).
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- **It is validated, not vibes.** Three core predictions are exact closed forms; the neural and
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image results confirm the *signs* in real trained weights; 122 automated tests pass; the whole
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study is laptop-reproducible from a seed.
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- **It gives concrete design rules** for anyone building self-improving or model-merging systems:
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ground where it matters, merge-don't-average, match recombination to skill-entanglement, select
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offspring, keep diversity, and gate irreversible consolidation on health.
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*The remaining frontier is the **LLM instantiation** — realising the grounded sexual society with
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actual language models (LoRA specialists, real model merging, execution-verified grounding), which
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the blueprint frames as the eventual empirical rung.*
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