Safe Evolution with Circuit Anchors

arXiv:2608.05158v1 Announce Type: new Abstract: In biological evolution, unconstrained mutation can lead to catastrophic outcomes: organisms may evolve enhanced capabilities while losing essential functions for survival. Nature's solution is extit{developmental constraints}, where core regulatory genes remain anchored while peripheral genes adapt freely. We observe that current self-evolution algorithms for large language models lack analogous constraints. They optimize purely for capability, implicitly assuming safety will be preserved. Our experiments reveal this assumption to be dangerously wrong: models can extit{misevolve} into powerful yet dangerous entities. Inspired by how Hox genes anchor body structure across 500 million years of evolution, we propose extbf{Circuit-Anchored Evolution (CAE)}. Using mechanistic interpretability, we identify a tiny extit{safety circuit}, comprising less than 2% of model features, that causally mediates safety behaviors. We anchor this circuit during evolution, constraining it within a small displacement bound while allowing the remaining features to evolve freely. This mirrors the biological principle of extit{evolvability with constraint}: preserving what is essential while adapting what is peripheral. Experiments across 3 model families and two evolution algorithms demonstrate that CAE achieves superior safety preservation with minimal capability loss, substantially outperforming explicit reward-based constraints in both effectiveness and efficiency. Just as developmental constraints prevent biological evolution from producing nonviable organisms, circuit anchoring prevents model evolution from producing capable but dangerous systems.

Source: arXiv cs.CL | 2026-08-07