of globalization were also a relatively few people in the already-rich countries, a global plutocracy who also experienced income gains of over 50 percent, but from a much higher starting point. Both of these changes are without precedent in the history of humanity.

But the elephant curve also shows that even though some have gained, others have not seen their prospects improve at all—indeed, probably leading lives of more insecurity and more worry, not just about their prospects but also the prospects of their children. The big losers in these global income sweepstakes have been middle and lower-income people of the rich countries—the part of the curve that shows the big dip. It is their plight, and its sharp contrast with the rich and richer minority in their countriesforth a theory to explain the long-run trends of within-country inequality.

The starting point is the Kuznets curve, the 1950s idea from Simon Kuznets that economic growth first raises inequality, before causing it to fall. The transition from an agrarian economy to a manufacturing economy leads to higher incomes as workers move to better-paying urban jobs, and as entrepreneurs make gains from the higher returns on their capital. But eventually labor becomes scarcer in the rural areas, switching the demand-supply calculus and lowering the margin for profits, both forces signaling the beginning of a slide down the Kuznets curve to lower inequality.

Thomas Piketty did much to challenge this idea in his book Capital in the Twenty-First Century, suggesting it is contradicted by the major increase of inequality in countries