RED HERRING. “Although not observed in the comparatively small rodent species analyzed, the enlargement of the cerebral cortex is not, in principle, an exclusive feature of the human brain: a similar expansion of the mass of the cerebral cortex, relative to the whole brain, is predicted by both the rodent and primate cellular scaling rules, irrespective of the number of neurons contained in the cortex.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2776484/