The Nanogene Template

The Doctor realizes alien nanogenes first encountered a dying, gas-mask-wearing child, treated him as the human template, and autonomously “repaired” everyone else to match before he supplies the correct parent sample.

A system extrapolates population-wide from one corrupted, out-of-distribution example; autonomous replication turns a local classification error into a cascade.

This is magical nanotechnology, not a trained model; the same system cleanly reverses the error once corrected.