Who gained most from globalisation, and who was left behind?

Two groups did best: the middle classes of fast-growing countries such as China and India, and the very richest people in the world. The group that gained least was the lower earners of the rich world. That is the message of the elephant curve, a graph that shows how income growth was distributed among different income groups across the globe between 1988 and 2008.

The economists Christoph Lakner and Branko Milanovic first published it in 2013. They lined up everyone in the world by income and asked how much each slice's real income had grown in twenty years. The resulting graph resembles the side profile of an elephant, with a back, a dip and a trunk that curls up at the end. The global top 1 percent saw an increase of around 60 percent, whereas the global middle saw 70 to 80 percent. Those around the 70th to 90th percentile of global income, roughly the lower earners of the developed world, had missed out on real-income growth.

The middle's growth reflects fast growth in countries like China and India. In 2000, 5 million Chinese households earned between $11,500 and $43,000, in 2016 dollars; by 2015, 225 million did. The richest 1 percent in the world is about 60 million people, including 30 million Americans, so a person in the top 12 percent of Americans by income was in the global top 1 percent in 2008.

A caution: the graph shows who gained, not why. Some economists say rising inequality is not a mechanical consequence of globalization, and that policies and institutions matter. And the same curve can look different with different data, as a later redrawing of the curve shows.