The Longevity Revolution

How average lifespans have risen dramatically over the past century, why it happened, and why it counts as one of humanity's greatest achievements.

In 1900, average life expectancy around the world was roughly 32 years, largely because many children died young. Today, it is over 70 years, according to United Nations estimates. This longevity revolution is one of the most remarkable changes in human history.

Why lives got longer

Lower child mortality: vaccines, clean water, sanitation and better nutrition sharply reduced deaths from infectious disease in childhood.
Medical advances: antibiotics, treatments for heart disease and cancer, and safer childbirth.
Rising incomes, allowing better food, housing and health care.
Public health measures, such as reducing smoking.

In early decades, most gains came from saving children. More recently, gains have increasingly come from helping older people live longer.

Differences between countries

Life expectancy varies widely: Japan’s is among the highest, at around 84 years, while some countries in sub-Saharan Africa have life expectancies in the low 60s. India’s life expectancy has risen from around 32 years at independence in 1947 to around 70 today.

Economic value of longer lives

Economists have tried to measure the value of longer life. Research by Kevin Murphy and Robert Topel estimated that gains in U.S. life expectancy during the twentieth century were worth trillions of dollars, comparable to all the growth in measured income. Longer, healthier lives are a huge part of rising living standards, even though GDP does not count them directly.

New questions

Longer lives raise economic questions this module explores: how to pay for pensions and care, how long people should work, how to keep older people healthy, and how businesses can serve older consumers.

The value of extra years

Imagine two countries with the same income per person. In one, people live to 60 on average; in the other, to 80. Measured by GDP, they look equally well off. But people in the second country enjoy twenty more years of life. Economists argue that ignoring longevity greatly understates how much living standards have improved.

Thinking ageing is only a problem

Population ageing creates challenges, but it results from a great success: more people surviving to old age. The goal is to adapt economies and institutions to longer lives, not to regret them.

Key takeaways

Global life expectancy rose from around 32 years in 1900 to over 70 today.
Lower child mortality, medicine, incomes and public health drove the gains.
India's life expectancy rose from around 32 at independence to around 70.
Longer lives are enormously valuable, even though GDP does not count them.