How did the super-smart help economies grow? Other analyses by Ms Squicciarini and Mr Voigtländer suggest an answer: “upper-tail knowledge raised productivity in innovative industrial technology”. In other words, when the Industrial Revolution came along, the “Encyclopédiens” were the ones who could convert the technological improvements into industrial ones. The companies they helped build needed ever-smarter workers, but it was high super-smart density, not high average worker skill, that provided the initial economic magic.