Since we are for the most part the descendants of the strivers of the pre-industrial world, those driven to achieve greater economic success than their peers, perhaps these findings reflect another cultural or biological heritage from the Malthusian era. The contented may well have lost out in the Darwinian struggle that defined the world before 1800. Those who were successful in the economy of the Malthusian era could well have been driven by a need to have more than their peers in order to be happy. Modern man might not be designed for contentment. The envious have inherited the earth.

Gregory Clark, A Farewell to Alms: A Brief Economic History of the World, Princeton, 2007, p. 16