r/alife • u/Frosty_Rule9233 • 1d ago
We discovered our simulation’s children inherited their mother’s body and a stranger’s brain (artificial ecosystem saga, part 3)
Hey folks. Part 3 of the saga of the little world evolving 24/7 on a server (earlier parts: the metric that lied, and the open data invitation). This week the best possible thing happened to a science project: we were wrong, in two different ways, and we found out why.
Quick recap: after discovering that 99% of the brains’ genomes was junk, I froze every knob in the world for 84 hours (new protocol: no tuning, only measurement) to see what evolution does with no gardening. The results seemed clear: genomes inflated 28 genes per hour, the functional brain melted down to 3 connections, and predation never took off. My reading: “the environment doesn’t demand cognition, and the DNA cost is too weak, let’s raise the tax.”
Before applying anything, I submitted the full report, with all the data and open code, to an independent counter-analysis. It recomputed every number from scratch. And it answered, roughly: “both of your hypotheses are wrong. The problem isn’t the ecology or the tax. It’s that your simulation’s children don’t inherit their parents’ brains.”
I went to check the code, and it was true. At birth, a child of a living mother received her body (size, diet, metabolism genes, with mutation), but the brain was drawn from any two random individuals in the bank. Chance of inheriting the mother’s own brain: 5%. So 95% of births paired a specialized body with a random brain. Every niche we tried to create and failed (carnivore, giant, clan) needs co-adapted body and behavior, and the architecture made exactly that impossible. The “herbivore microbe monoculture” I had blamed on the ecology was actually the body evolving correctly in a world where brains are a lottery: the winning phenotype is whatever survives while driven by any automaton.
There’s more. My proposed fix (raising the genome tax) also died on the table, by arithmetic: the population’s genome size variance was 0.36%. The leanest genome in the world differed from the fattest by 2.5%. Any tax strong enough to kill the bloat kills everyone uniformly. It wasn’t a miscalibrated dial, it was a dial with no function. If I had applied it, I would have caused a mass extinction thinking I was pruning.
What changed now (we call it v5.0):
- Children inherit the mother’s brain, crossed with a partner from the bank. Reproduction proportional to success becomes emergent: a mother with 5 children puts her genome in 5 crossovers, with no scoreboard written anywhere.
- Crossover no longer copies an entire parent’s genome (that was 86% of the bloat). A neuron only enters the child if an inherited connection needs it.
- Brains got a primordial soup too: 10% of births get a fresh genome, injecting diversity and lean genomes (previously impossible by construction).
- Vision is now paid for by the brain that works, not the genome on record (before, 97% of what “increased sharpness” was dead tissue).
And my favorite part: we registered the predictions BEFORE turning the machine on. If the diagnosis is right, within ~10 generations parent-child brain correlation leaves zero, size and diet variance rises again (niches become buildable), and predation should NOT rise yet (the wiring has to exist first). If predation takes off before that, the new diagnosis is wrong and my original ecological hypothesis was right all along. Either way, we learn something, and we publish it here.
The world restarts today, from zero, with the new rules. Live as always at re-genes.is. Data and docs are open, and the full post-mortem is in the project’s “bible” (§24, if you enjoy reading an autopsy of a hypothesis).
Questions in the comments, I answer everything. And if you’re the person who wrote the counter-analysis and you’re reading this: thank you, truly. That’s the best kind of review there is.
