A fishy perspective on the social brain hypothesis

Ectotherms, particularly fish, challenge traditional brain evolution theories by exhibiting advanced cognitive abilities despite their smaller brains. While the social brain hypothesis may apply within clades, sensory-motor systems likely explain the brain size differences between average-brained ectotherms and endotherms. Evolved complex sensory-motor systems suggest that brain evolution models should expand to include sensory and motor systems, beyond cognitive processes alone.