CityReads|How Humans Gained Twenty Thousand Extra Days of Life？

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How Humans Gained Twenty Thousand Extra Days of Life？

Four key tools to extend human lifespan: vaccines, drugs, data, and behavior.

Steven Johnson, 2021, Extra Life: A Short History of Living Longer, Riverhead Books.

Extra Life: A Short History of Living Longer, 2021. PBS documentary.

Sources:

https://www.penguinrandomhouse.com/books/594501/extra-life-by-steven-johnson/

https://www.pbs.org/show/extra-life-short-history-living-longer/

In the early 1660s, when people first started tinkering with the idea of calculating life expectancies, the average British person lived just over thirty years. But a child born in the UK today can expect to live a full fifty years longer than that.

And that extraordinary upward slope has been repeated again and again around the world. Between 1920 and 2020, the average human life span doubled.

All the advances of the last three or four centuries—the scientific method, the medical breakthroughs, the public health institutions, the rising standards of living—have given us about twenty thousand extra days of life on average.

Then, how many of those extra twenty thousand days came from vaccines, or randomized, controlled double-blind experiments, or the decrease in famines?

In his new book, Extra Life: A Short History of Living Longer, science writer Stephen Johnson attempts to answer this question by looking at the concept of life expectancy and how eight factors—vaccines, data and epidemiology, pasteurization and chlorination, regulations and testing, antibiotics, safety technology and regulations, and anti-famine interventions—have come together to drive the doubling of human life expectancy in the last 100 years.

The book is accompanied by a documentary with the same name, which premieres on PBS on May 11, 2021. In the film, Stephen Johnson and historian David Olusoga tell the stories behind the forces that extends our lives and the stories behind these extraordinary breakthroughs. The four-part documentary reviews how vaccines, medical drugs, data and behavior became some of the most powerful tools we have in the fight for extra life, discovers the little-known story of the innovations in science and medicine, and investigates the forgotten heroes of global health, including scientists, doctors, researchers and activists. Each of the four episodes will take a historical approach to investigating one aspect of medicine and public health that has played a central role in doubling human life expectancy over the last 100 years.

Vaccines

For centuries, the world was at the shadow of smallpox which made average life expectancy tragically low. The first medical intervention that extends human lifespan was developed precisely to combat this ancient threat.

In a record of a conversation between Cotton Mather and his African slave Onesimus, Onesimus mentioned an African procedure that had unknown in the West. An incision is made in the skin and a tiny amount of fluid infected with smallpox is smeared into the cut. Though this deliberately causes a mild illness, crucially, it protects against a more deadly full-blown smallpox infection. It's called variolation and it is the forerunner of vaccination. Variolation was first used in China in the 16th century, and by the 17th century it had spread to India, parts of Africa, and Persia, where it was probably invented independently one after another. It was not until the 18th century that Variolation was introduced to Europe and North America.

Cotton Mather

In 1721, a British ship arrived in Boston carrying smallpox, starting an outbreak. Mather tried to promote variolation, but was resistant by the public and medical establishments who were dubious about medical knowledge from Africa. As smallpox raged through Boston, more than half population were infected and 850 people died. But Mather persuaded a small number to undergo variolation and among them, the death rate dropped to around 2%.

On the other side of the world, a British aristocrat, Lady Mary Montagu, introduced variolation into England from Ottoman Turkey. She successfully variolated her daughter and a five-year-old son, and also, persuaded Princess Caroline, the wife of the future George II, to have two daughters variolated. Royal endorsement led to the development of the variolation in Britain. The story of Lady Montagu demonstrates the transmission of a new medical technology from one society to another, in which elite advocacy is very significant.

Lady Mary Montagu

In the second half of the 18th century, life expectancy for the elite of England increased almost in a straight upward line, but at the same time the rest of the country remained stuck at 35, and for the first time there was a gap in life expectancy among different classes. So it's both the beginnings of the great escape into longer life and the beginning of health inequality.

Later, Edward Jenner found that milkmaids caught cowpox, a mild skin disease, but they rarely caught smallpox. He thought that perhaps catching cowpox prevented milkmaids from catching smallpox. He chose an eight-year-old son of his gardener to test his theory and succeeded. Over the next 50 years, vaccination saved lives.

Over the next 50 years, vaccination cut deaths from smallpox in London.

Jenner's technology to address smallpox was spread around the world in exactly the same currents as the disease, trade, empire, migration, movement. In early 1800s, Benjamin Waterhouse brought Jenner's vaccine to America and wrote to influential people, including the President of United States, Thomas Jefferson. Jefferson was interested about it and began his vaccine trial on several hundred people on his estate, among which enslaved people he owned was experimented on first. This story is also relevant to current anti-vaccination movement. Historically, black people have often been the subject of unethical medical trials, so many of the communities resistant to vaccines are African Americans in the US and ethnic minorities in the UK.

Progress in medicine or any other form has been achieved not only by standing on the shoulders of giants, but often on the broken bodies of those who had little say in how they were used. The history of human lifespan extension has been continuously influenced by changing power dynamics, including the repeated exploitation of the disenfranchised.

In 1958, the height of Cold War, the Soviet deputy health minister called on member countries of the World Health Organization to dedicate to eradicate smallpox together. A decade later, 73 countries, including the United States and the Soviet Union, working together to vaccine the planet. And freeze drying developed in the 1950s, cumbersome jet injectors developed in the 1960s, and the idea of ring vaccination made it possible to vaccinate everyone. Until 1975, smallpox has gone the moment a last young girl was cured in Bangladesh.

It's estimated that 300 million people died from smallpox in the 20th century, more than three times the number killed in the two world wars.

Medical drugs

In 1900, life expectancy in the US was just 49 years. But three decades later, the discovery of penicillin profoundly changed drugs and medicine, causing life expectancy in the US to rocket upwards.

In London 1928, Alexander Fleming found something literally in the air could be a bacteria killer accidentally. However, the development of the drug itself got paused for a decade after Fleming's discovery.

Alexander Fleming

In Oxford 1938, Howard Florey, running an institute of pathology, read Fleming's paper. He and two other biochemists, Ernst Chain and Norman Heatley, worked together to produce a tiny amount of penicillin within a few months and proved in controlled experiments that it could fight bacterial infection. They scaled up production of penicillin, and, in February 1941, administered it to Albert, a man infected bacteria caused by a cut from plants. Within hours, Albert seemed to recover, but the penicillin was running out and he died in March 1941. But it already proved that penicillin was effective, and now they faced the almost impossible task of producing enough penicillin to treat more people.

Howard Florey, Ernst Chain and Norman Heatley

In July 1941, without support from British government and pharmaceutical companies, Florey and his team continued their research in New York, where they met talents of specialisms and skills and received government support. Years later, American company Pfizer decided to help them mass produce penicillin. The idea was to blow air through a nutrient-rich broth, and they executed it on a industrial scale. The result was spectacular that the yield was five times the highest estimate.

The arrival of penicillin transformed many deadly diseases into treatable ones overnight. Antibiotics have helped to get rid of diseases like tuberculosis and syphilis, extended global life expectancy by two decades and opened the door for the next generation of medical drugs.

Penicillin solved the problem of bacterial infections, but not yet viral infections. Until 1970s, a pioneer called Gertrude Elion began using new scientific methods to custom build effective antiviral drugs. Elion and her team built highly efficient targeted drugs through careful study of how cells interact with compounds and pathogens. In 1978, Elion presented a paper on a miraculous new compound in a conference. It’s the first highly selective antiviral drug targeting the herpes virus, called acyclovir. It ushered in a new age of medicine, this time targeting viruses. Many designer drugs emerged to help treat a huge range of illnesses from leukemia to malaria to arthritis.

Gertrude Elion

Now, we're constantly creating new designed drugs against new viruses, and also innovating in drug discovery technology. New threats such as HIV and COVID-19 inevitably emerge, but scientists have also discovered designed drugs such as protease inhibitors and SARS-COV-2 to combat them. And applying artificial intelligence to drug discovery period makes it possible to find effective drugs among a large number of molecular within a short time.

Halicin, a molecule discovered by AI and that could become first new class of antibiotics in decades.

In modern drug development, it takes less time to develop a new designed drug and it's a much more rational process instead accidents, and also a story of the sharing of information globally, instantly among medical teams.

Data

Using data to stop epidemics roots in Victorian Britain. The London of the mid 1800s had already been through three cholera epidemics, life expectancy struggling to get above 37 years. In 1866, cholera swept through London, and the death toll soared in a short time. This cholera was a medical mystery. Because there had been no cholera outbreak for a decade, and over this decade London had built a huge sewer system to prevent disease.

Medical statistician William Farr hoped to use data in real time to understand the latest cholera epidemic. In Farr's life tables, he examined not only the time of death, but also the cause, age, occupation, and place of residence. Knowing the cholera is transmitted in the water, he added a new category of information, the water company that supplies each victim's drinking water. Farr worked out that the great majority of the cholera cases are connected to the East London Waterworks Company, and so immediately he had warned people in the affected areas not to drink unboiled water. It was eventually found that local water pollution had affected the water company, which led to cholera. Within weeks, the waterworks had been cleaned up and the source of the outbreak was stopped dead in its tracks. And cholera was eventually driven out of London by data, never to return.

Farr's Curve: It's discovered by William Farr that epidemics rise and fall in a symmetrical pattern.

In coronavirus pandemic, by detecting and tracking rising case loads, we get ahead of William Farr's epidemic curve. Scientists even test the sample form wastewater with PCR (polymerase chain reaction) to reveal hotspots of coronavirus before people show symptoms. Wearable teches are also being developed to detect COVID-19 by monitoring physiology indicators before symptoms appear.

Use wearable devices to monitor physiological indicators.

Health inequalities have been stark during coronavirus pandemic, especially for African-American and Hispanic communities. This is not due to genetic variation, but mainly on the basis of their social environment. Black and Asian communities are more likely to live in multi-generational households, and their work requires more direct, face-to-face contact, so they are at higher risk of infection and higher mortality.

The risk of death increases for the Black and the Asian ethnicity in 30 days from hospital admission during COVID-19 pandemic.

There was a time when racism and racial disadvantage were rampant. But when Du Bois surveyed Philadelphia's 7th Ward in 1890s, he found that health problems of Blacks in the 7th ward weren’t caused by some natural inferiority, but that poor conditions were shortening black lives. In 1900, he exhibited at the World Expo in Paris an astonishing visualization of data collected on the legacy of slavery and racism. To improve life expectancy of African-Americans, he argued, the entire environment and economic system around them must change.

In late 1950s, Herbert Needleman has tracked children's lead levels and its influence over many years by collecting kids' teeth. And the data published in 1972 revealed that inner-city kids living in older buildings and exposed to greater traffic pollution had five times more lead in their bodies than kid from the suburbs. It also showed that children whose exposure to lead was highest, scored 4 points lower in IQ tests. And when he continued to study the children as they grew up, he found greater high school dropout rates, poorer eye coordination and other persistent problems even a decade later. The data showed conclusively that lead was harming the long-term health of children. His research was discredited and undermined by the lead industry, but was eventually accepted as the scientific consensus that led to the removal of lead from household products, gasoline.

Herbert Needleman

Herbert Needleman's data reveals that inner-city kids living in older buildings and exposed to greater traffic pollution had five times more lead in their bodies than kid from the suburbs.

So, data says the true cause of the disease and reveals the true problem.

Behavior

In the 19th century, cities were unimaginably filthy, becoming the breeding ground for many deadly diseases, and people did not understand the importance of hygiene and sanitation yet.

In 1846, a young Hungarian doctor, Ignaz Semmelweis, landed the job of assistant physician at Vienna General Hospital. This hospital had two birthing wards, one staffed by doctors and the other by midwives. But in doctor-led ward, many women died of fever shortly after childbirth, death rate of this ward far higher than in the other. In days before microscopes, Semmelweis accidentally found that some kind of invisible deadly particles in the hands of doctors killed mothers. He proposed that all doctors delivering babies in ward must wash their hands after dissections. Semmelvis blamed the doctor for the death, and he was only a junior doctor in that hierarchical society and profession, so his ideas were rejected by the medical establishment and he came to a miserable end.

Ignaz Semmelweis

Elsewhere in Europe, the idea that cleanliness saved lives was spreading. After analyzing the death causes of British soldiers in the Crimean War, Florence Nightingale argued that poor hygiene led to diseases that were more deadly than gunfire. She designed a rose diagram to show that disease was the big killer in the Crimean War. Her ideas contributed improvements in hospital conditions, and by the end of the year the number of soldiers dying from disease had fallen by 99%. Nightingale's ideas were recognized not only for her statistical genius, but also for her social status, born as an aristocrat and becoming a national hero back from the Crimea.

Florence Nightingale

Rose diagram designed by Nightingale. Each rose petal represents the number of soldier death in a month. Different colors represent different causes of death—pink for wounds, blue for infectious diseases, and black for other causes.

Nightingale's work also coincided with a period of intense scientific discovery in hygiene. All of them eventually persuaded the medical establishment that hygiene was the first line of defense against disease and to promote behaviors like bathing and hand washing with soap, which extended life expectancy.

Actually, changing behavior is very difficult, and maintaining that change can be even harder. Psychologists discovered a gap between what people intend and what they actually do. Behavioral scientists once designed the hand-safety stamp to remind workers of washing their hands by providing a visible symbol and based on fears of shame or social rejection.

To fight the virus during COVID-19 pandemic, we need to adapt to new rules and behaviors, like wearing masks and maintaining social distance, But the truth is, we've been here, in the 20th century.

In 1918, the Spanish flu swept army barracks across the US. The US surgeon General warned that influenza is a crowd disease and all social gatherings must be avoided to save lives. Philadelphia Public Health Chief, Wilmer Krusen, ignored pandemic warnings and did not stop a massive parade to raise money for the war. But Seattle's health chief, J.S. McBride, took a dramatically different course of action. He closed all schools, libraries, dance halls, pool rooms, cinemas and churches, recruited a flu squad to patrol the streets, required people to wear bulky masks with six-ply gauze and even published the names of violators in newspapers. A month later, death rate of Philadelphia was roughly six times higher than that of Seattle. Seattle enforced restrictions, increased them, and maintained them over a long period of time, ultimately contributing to their success.

In October 26th, a month after the outbreak, the excess death rate per 100,000 in Philadelphia is around 250, while in Seattle it’s about 40.

Leadership decisions have played a crucial role in Seattle's success, but sometimes, the most transformative power comes from the grassroots. In 1980s New York, in the midst of the AIDS crisis, changes began within the gay community. Without no support from the government, medical establishment or public groups, Richard, who was infected with AIDS, and his friends published a pamphlet, How to Have Sex in an Epidemic. It explained how the virus got transmitted sexually and only using a condom could protect people and their partner. The pamphlet quickly spread in gay community and helped stem the AIDS crisis.

Richard and the pamphlet How to Have Sex in an Epidemic

The past two centuries has taught us many lessons, and we need to change our behavior to fight the COVID-19.

Will human life expectancy continue to extend?

A century of rising life expectancies has made that upward march seem almost inevitable: the Moore's Law of public health. But what if those extra twenty thousand days turn out to be an anomaly? In the United States, for the first time since the end of the Spanish flu, average life expectancy has decreased for three straight years.

The greatest threat to the twenty thousand days of extra life that we have fought so hard—on so many fronts—to achieve is one that, paradoxically, was made possible by that very same triumph. If a hundred years from now life expectancy has declined, the most likely culprit will be the environmental impact of ten billion people living in industrialized societies. Extending our lives gave us the climate crisis. Perhaps the climate crisis will ultimately trigger a reversion to the mean.

No place on earth embodies that history and that potential future more poignantly than Bhola Island, Bangladesh. Four decades ago, it was the site of humanity's most extraordinary achievement in the realm of public health: the elimination of smallpox, realizing the dream that Jefferson had envisioned almost two centuries before. But in the years that followed smallpox eradication, the island was subjected to a series of devastating floods; almost half a million people have been displaced from the region since Rahima Banu Begum contracted smallpox there. Today large stretches of Bhola Island have been permanently lost to the rising sea waters caused by global warming. The entire island may have disappeared from the map of the world by the time our children and grandchildren celebrate the centennial of smallpox eradication in 2079. Or will those momentous achievements—all that unexpected life—be washed away by an actual tide?

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