> Strategic mistakes will be made by rulers, but will also be made by local rulers and individual families. "Should we plant corn or wheat this year?" - someone with intellect may read a book to discover the best crop or do a small scale trial, while someone with lead poisoning may just do the same as he did last year because it takes less mental effort.
That seems to be transplanting modern education and growth norms onto a historic situation. Roman literacy was exceptionally high by the standards of ancient civilisation, which meant that one in ten people (probably not farmers) could read a book and doing the same as last year or as their ancestors was the rule rather than some sort of anomaly. People smart enough to make substantial changes would tend to be stopped far more by social structures than any minor slowdown to their cognitive abilities. In that sense, if lead poisoning had effects on modern information and intellect driven civilisations so small it took some pretty thorough statistical analysis against a backdrop of rapid growth to convince us there was anything to the theory at all, it seems unlikely it could have made so much more difference to daily life in Ancient Rome. A cognitively impaired Emperor could do a lot of damage, but the inherent flaw in the system was that sort of power also flowed to natural born idiots and every civilisation has those.
That seems to be transplanting modern education and growth norms onto a historic situation. Roman literacy was exceptionally high by the standards of ancient civilisation, which meant that one in ten people (probably not farmers) could read a book and doing the same as last year or as their ancestors was the rule rather than some sort of anomaly. People smart enough to make substantial changes would tend to be stopped far more by social structures than any minor slowdown to their cognitive abilities. In that sense, if lead poisoning had effects on modern information and intellect driven civilisations so small it took some pretty thorough statistical analysis against a backdrop of rapid growth to convince us there was anything to the theory at all, it seems unlikely it could have made so much more difference to daily life in Ancient Rome. A cognitively impaired Emperor could do a lot of damage, but the inherent flaw in the system was that sort of power also flowed to natural born idiots and every civilisation has those.