Millennia of stagnation then exponential growth
For roughly 1,500 years before 1800, global per-capita GDP remained relatively flat despite technological innovations and trade expansion. Growth rates averaged near zero or slightly positive, constrained by agricultural limits: most humans farmed, famines recurred regularly, and disease killed a steady percentage of populations. Wealth accumulated in cities and courts, but ordinary living standards barely rose.
The Industrial Revolution inverted this pattern. Between 1800 and 2020, global per-capita GDP increased roughly 10-fold (adjusted for inflation). The inflection occurred not at a single moment but across the late 1700s, as steam power, mechanized textiles, and iron production began multiplying human output per worker-hour.
The divergence between continents
Industrial growth was geographically concentrated. Britain industrialized first (1770-1850), followed by Western Europe and North America (1850-1950). Today's wealthy nations (US, Germany, Japan, Switzerland) are descendants of early industrial nations or their settler colonies. Nations that industrialized late or not at all (colonial Africa, large parts of Asia) saw living standards rise much later, explaining persistent gaps.
This divergence created the modern world: a small cluster of high-GDP nations (GDP per capita above 50,000 USD) surrounded by middle-income nations (5,000-20,000) and low-income nations (under 2,000). Catch-up growth exists but is slow; a nation must accumulate capital, skills, and institutions over decades to close a half-century development gap.