The Great Convergence

In 1960, the most consequential fact about a newborn was the country named on its birth certificate. A baby born in the United States that year could expect to live nearly seventy years. A baby born in Nigeria — in the very year seventeen African nations declared independence — could expect fewer than forty. The difference was not a statistic. It was a sentence, handed down at birth.

Six decades on, that sentence has been commuted almost everywhere. The defining health story of the modern era is not rich countries pulling further ahead. It is poor and middle-income countries closing the distance, at a pace almost no one in 1960 thought possible.

Follow the lines below. South Korea enters the chart as a poor, war-scarred country whose citizens lived into their early fifties; today it outlives the United States by a comfortable margin. China climbs through famine, upheaval and reform to draw level with the rich world. India and Brazil each add more than two decades of life within two generations. Even Nigeria — the laggard of this group, and a standing reminder that convergence is unfinished — gains more years over the period than the United States does.

The mechanisms behind this convergence were almost aggressively unglamorous. Vaccination campaigns. Antibiotics. Oral rehydration salts — a sachet of sugar and minerals that costs pennies and stops a child dying of diarrhoea. Clean water, girls' schooling, the slow spread of basic clinics. Smallpox, still killing at the start of this chart, was eradicated from the wild by 1980. None of it made headlines the way wars and famines did, and all of it shows up in the data as the same signature: a long, patient, upward grind, occasionally interrupted — and then resumed.

The health gap has not closed. But it has narrowed from an abyss into a distance a single generation can cross.

Where the years came from

Most of the added years were not tacked onto old age. They were rescued from infancy. In 1960, across much of Asia and Africa, more than one child in five died before a fifth birthday. Mortality on that scale shaped everything it touched — family size, women's lives, the whole arithmetic of grief.

The under-five mortality chart is the convergence's engine room. Its lines fall so steeply that the eye reads them as collapse, and collapse is the right word: in much of the world, child death rates have fallen by roughly ninety percent since 1960. No other number in this dataset has moved so far, for so many people.

South Korea is the standout: the country that traveled furthest, fastest. Within a single lifetime it moved from the mortality profile of a poor agrarian society to one of the longest-lived populations on Earth, overtaking nearly every country that was rich while it was poor. Nothing in the 1960 numbers predicted it — which is precisely what makes the line worth staring at.

Honesty requires the caveats. Sub-Saharan Africa still trails the rich world by roughly two decades of life, and gaps within countries can rival the gaps between them. The AIDS epidemic carved a visible crater through southern Africa's lines in the 1990s that took twenty years to refill, and the pandemic bent every line downward at once.

But zoom out to the full sweep of the chart, 1960 to now, and the signal overwhelms the noise. The twentieth century's cruelest lottery — the one drawn at birth — is slowly being rigged in humanity's favor.

Every figure identifies its source. See SPHRE sources and methodology.