Does Size Matter? Cross-Species Analysis of Intelligence and Brain Size

Brain size correlates weakly with intelligence within species yet strongly across species, and several taxa—from corvids to honeybees—exhibit cognitive abilities disproportionate to their brain mass. The Strong Electromagnetic Field Hypothesis (SEFH) proposes that higher cognition emerges from hierarchically nested electromagnetic (EM) field dynamics in neural tissue, generating predictions based on two variables: (i) wattage density—EM field production intensity per unit volume of integrative tissue, driven by neuron density—and (ii) harmonic capacity—the number of distinct geometric eigenmodes (resonant standing-wave patterns) that the field-permeable tissue can sustain. We test these predictions using comparative neuroscience datasets across primates, corvids, parrots, cetaceans, elephants, carnivores, rodents, and honeybees. After excluding cerebellar neurons, we find that SEFH predictions are confirmed across key comparisons: corvids and parrots achieve primate-rival cognition with 3–5× higher pallial wattage density than human cortex; honeybees achieve remarkable cognitive feats with ~960,000 neurons/mg; and elephants dramatically underperform even when cerebellar neurons are excluded. A preliminary two-variable regression of the form cognitive capacity ∝ wattage density × log(harmonic capacity) explains over 90% of cross-species cognitive variance (R² = 0.918), confirmed by leave-one-out cross-validation (R² = 0.761) and permutation testing (p < 0.001). The model’s algebraic form—log(density² × volume)—yields a natural physical interpretation as total EM field energy in integrative tissue.