Emerging economies grew fast by turning towards trade

Some low- and middle-income economies have grown faster than high-income ones, so their incomes are catching up. China and India, with more than a third of the world's population between them, are two of the fastest growers. Many of the economies that grew fastest in recent decades, including South Korea, China and India, did so by orienting their economies towards international trade. As they grow, they buy and sell more abroad, so a larger share of world trade runs to and from them.

Comparative advantage shifts as countries build new skills

Comparative advantage is not fixed by climate or geography. Firms that specialise in particular products learn and gain economies of scale, so the goods a country makes at the lowest opportunity cost change over time. Firms also split production into stages and place each where it costs least: a phone can be designed in one country and assembled in another. As trade grows, jobs move away from industries where a country has lost its comparative advantage and towards those where it has one.