Determine the origin of the persistent 3D performance ceiling

Determine whether the persistent performance ceiling observed after transferring the co-evolved communication controllers from the two-dimensional simulator to the three-dimensional physics-based simulator is caused primarily by limitations of the controller architecture or by insufficient evolutionary incentives for developing behaviors unnecessary in the two-dimensional environment.

Background

The transferred controllers achieved substantially lower performance in the three-dimensional physics-based simulator than in the two-dimensional simulator. The discussion identifies two principal explanations: the recurrent controller architecture may be inadequate for the physical environment, or the evolutionary fitness incentives may not have selected behaviors needed only under three-dimensional physical constraints.

The paper reports that the available experiments cannot distinguish these explanations. The observed asymmetry between the two independently evolved roles suggests that evolutionary dynamics may contribute, but the cause of the persistent performance ceiling remains unresolved. This question is therefore directly connected to understanding and reducing the simulation-to-simulation transfer gap.

References

The above reformulates the central question of this work: why does a performance ceiling persist in 3D? One possibility is a limitation in the controller's architecture. Another is a limitation in evolutionary incentives. In the latter case, fitness pressure would have been insufficient for behaviors to emerge that were never necessary in the 2D environment. The results of this work do not allow us to definitively answer this question, but they do help to narrow it down. The results of this work do not allow a definitive distinction between architectural and evolutionary explanations.

— Evaluating the Transfer of Co-Evolved Communication from 2D to 3D Simulation  (2610.09280 - Montes-Gonzalez, 7 Oct 2026) in Section 4, Discussion, subsection “Same mechanism, different consequences depending on the body”