To illustrate this point, Kenny compares what has happened to life expectancy in Britain and India. The average age span in both countries was 24 years in the 14th century, but Britain then began a gradual rise, and by 1931 its life expectancy was 60.8 years, compared to just 26.8 for its colony. Since then, though, the numbers have begun to converge — by 1999, Indians lived on average to 63, while Brits nudged upward to 77.
One of the main reasons for the gap-closing is the fall of infant mortality. In 1900 Britain, the infant survival rate was 846 per 1,000 births, compared to 655 in India. Today, 992 British infants out of every 1,000 survive, compared to 920 Indians.
Kenny notes: “Broadly, the results suggest that it takes one-tenth the income to achieve the same life expectancy in 1999 as it took in 1870.
Why does it take so much less money to get these results than it used to?
Consider the virtuous circle of agricultural improvements, such as the way discovering how to properly use inorganic fertilizers boosted agricultural production, which increased the calories available to families, which in turn meant they didn’t need their kids to work the fields full time, thus permitting them to go to school to become literate, which enabled them to more effectively adopt even better farming techniques, and so forth. Literacy makes educating people about the germ theory of disease a lot easier. Once-expensive medicines like penicillin eventually cost only pennies per pill. Although building infrastructure remains relatively expensive, technology can leapfrog entire costly steps, as has been demonstrated by the lightning-fast growth of cellular-telephone adoption from zero to 1.5 billion people.
The world’s poor have clearly benefited enormously from spillover knowledge and technologies devised in the rich capitalist countries.