The evolution of our unique social intelligence may have initially begun as a simple matter of brain chemistry. Compared with other primates, modern humans have dramatically more dopamine in their striatum and less acetylcholine, a neurochemical linked to dominant and territorial behavior.

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The evolution of our unique social intelligence may have initially begun as a simple matter of brain chemistry. Compared with other primates, modern humans have dramatically more dopamine in their striatum and less acetylcholine, a neurochemical linked to dominant and territorial behavior.