Arithmetic mentality predates humans as birds count. Geometric mentality emerges from Paleolithic shamanic rites. H. sapiens displaced Neanderthals in Europe around 45-35 KYA during Middle-Upper Paleolithic transition. Franco-Cantabrian caves host creative explosion of art from 35-8 KYA. Shamanism defines Paleolithic religion with ecstasy, soul flights, fire mastery. Eliade links yoga, shamanism, alchemy to archaic techniques. McKenna claims psychedelics bootstrapped human evolution, religion, art. Paleolithic drugs like psilocybin fueled shamanic trances. Cave art splits into 70% geometric signs, 30% animals. Lewis-Williams' neuropsychological model ties art to trance entoptic phenomena. Klüver identifies peyote form-constants: gratings, tunnels, spirals. Von Petzinger catalogs 26 recurring geometric signs across 146 French caves. Top motifs: lines (70%), dots (42%), open angles (42%). Signs match Euclidean primitives: point, line, circle. Shamanic trances birthed pre-literate iconic language. Proto-geometry paves way for Neolithic arithmetic-geometric bifurcation.