"All human societies, from prehistory through to today, have been characterized by some degree of economic inequality. Arguably, complex societies would not have thrived if they had been unable to concentrate and redistribute resources effectively. We frequently talk about the top 5% or 1% today...

Earlier research on poverty failed to provide us with consistent measures of its prevalence across space and time. This is due to the limitations of the available sources and to the difficulty of applying to them the poverty definitions of modern social science. This article discusses different...