Thinking Citizen Blog — How Did the Human Life Span Double in Just 100 Years?

Thinking Citizen Blog — Thursday is Health, Health Care and Global Health Policy Day

Today’s Topic: How Did the Human Life Span Double in Just 100 Years?

The biggest news story of the last 100 years never made the headlines. Why? Three reasons. First, it happened in slow motion. Second, it was good news. Third, it’s measured in “nonevents” rather than “events” — eg. “the small pox that didn’t kill you.” But this week there was an article on the topic in the New York Times Magazine and I decided to share a summary with you. Experts — please chime in. Correct, elaborate, elucidate.


1. “One strange thing about the story of global life expectancy is how steady the number was for almost the entirety of human history. Until the 18th century, the figure appears to have rarely exceeded a ceiling of about 35 years, rising or falling with a good harvest or a disease outbreak but never showing long term signs of improvement.”

2. “A key factor keeping average life expectancy low was the shockingly high rates of infant and childhood mortality: Two in five children perished before reaching adulthood.”

3. “Human beings had spent 10,000 years inventing agriculture, gunpowder, double-entry accounting, perspective in painting — but these undeniable advances in collective human knowledge failed to move the needle in one critical category: how long the average person could expect to live.”

THE STANDARD EXPLANATION: Vaccines (Jenner), Germ Theory (Pasteur), Antibiotics (Fleming)

1. Vaccination: the benefits of small pox inoculation (1718) and vaccination (1796) was at first obscured by the negative impact of industrialization. Hero: Edward Jenner (1749–1823), “the father of immunology.” (First photo above)

2. Germ Theory: pasteurization turned animal milk from a “liquid poison” in the 19th century to an “icon of health and vitality” in the 20th. Hero: Louis Pasteur (1822–1895) “the father of bacteriology.” (Second photo above)

3. Antibiotics: Alexander Fleming’s discovery of pennicillin in 1928 has been called “the single greatest victory ever achieved over disease.”

THE UNSUNG HEROES: Nathan Strauss, John Leal, “Moldy Mary”

1. Pasteurization was resisted by the milk industry. It was the work of activists like Nathan Strauss (above) that got unpasteurized milk banned across the United States from 1900 to the 1920s.

2. The chlorination of the US water supply was the work of the unheralded physician and sanitarian John Leal (1858–1914). “In 1908, when Leal first started experimenting with chlorine delivery in Jersey City, typhoid was responsible for 30 deaths per 100,000 people. Three decades later, the death rate had been reduced by a factor of 10.”

3. While Fleming gets all the credit for penicillin “It took two Oxford scientists — Howard Florey and Ernst Boris Chain — to turn penicillin from a curiosity to a lifesaver, and their work didn’t begin for more than a decade after Fleming’s original discovery.” But the story does not end there. To get mass production you needed to identify a more productive mold. Here the unsung hero was Mary “Moldy Mary” Hunt, a bacteriologist in a lab in Peoria, Illinois.

THE PEAK AND FALL OF GLOBAL LIFESPAN INEQUALITY — the Green Revolution, rising standards of living, oral rehydration therapy

1. “In 1950, when life expectancy in India and most of Africa had barely budged from the long ceiling of around 35 years, the average American could expect to live 68 years, while Scandinavians had already crossed the 70-year threshold.”

2. “Global lifespan inequality peaked a decade after the introduction of antibiotics. “The gap between the West and the rest of the world has been narrowing for the past 50 years, at a rate unheard-of in demographic history. It took Sweden roughly 150 years to reduce childhood mortality rates from 30 percent to under 1 percent. Postwar South Korea pulled off the same feat in just 40 years. India nearly doubled life expectancy in just 70 years; many African nations have done the same, despite the ravages of the AIDS epidemic. In 1951, the life-span gap that separated China and the United States was more than 20 years; now it is just two.”

3. “The forces behind these trends are complex and multivariate. Some of them involve increasing standards of living and the decrease in famine, driven by the invention of artificial fertilizer and the “green revolution”; some of them involve imported medicines and infrastructure — antibiotics, chlorinated drinking water — that were developed earlier. But some of the most meaningful interventions came from within the Global South itself, including a remarkably simple but powerful technique called oral rehydration therapy.”

NB: Oral rehydration therapy (ORT) has been called “potentially the most important medical advance of the 20th century.” “As many as 50 million people are said to have died of cholera in the 19th century. In the first decades of the 21st century, fewer than 66,000 people were reported to have succumbed to the disease, on a planet with eight times the population.” Here the unsung hero was Dilip Mahalanabis, an Indian pediatrician, trained at Johns Hopkins, who led the effort to fight the cholera epidemic that broke out at the time of the Bangladesh war of independence in 1971.

THREE ADDITIONAL FACTORS IN GLOBAL SMALL POX ERADICATION: “ring vaccination,” “bifurcated needles,” and “heat-stable vaccine”

1. “Ring vaccination” — involved use of contact tracing. “In India alone, that kind of surveillance work required thousands of district health personnel, and more than a hundred thousand fieldworkers, overcoming challenging physical conditions and local resistance to do their work… During the final stages of the project, fieldworkers would visit each of the country’s 100 million households — once a month in endemic states, once every three months throughout the rest of the country — to trace the remaining spread of the virus.”

2. “Bifurcated needles” — required a quarter of the amount of the vaccine than prior methods and could be administered by non-specialists.

3. “Heat-stable vaccine” — could be stored unrefrigerated for 30 days.

For the last three years of posts organized by theme:

PDF with headlines — Google Drive


Please share the most interesting thing you learned in the last week related to health, health care or health care policy — the ethics, economics, politics, history…. Or the coolest, most important thing you learned in your life related to health are or health care policy that the rest of us may have missed. Or just some random health-related fact that blew you away.

This is your chance to make some one’s day. Or to cement in your mind something really important you might otherwise forget. Or to think more deeply than you otherwise would about something that matters.