Last November, I was invited to speak at a geopolitics conference in Central Asia. The meeting coincided with the centenary of the end of World War I, and I was given the job of opening the event with a short speech — 10 minutes or less — summing up the most important changes in the world in the 100 years since the guns had fallen silent.
This was quite a challenge. Still trying to decide what to say just three days before flying, I told my dentist about it when I visited him for a checkup. After laughing a little, he informed me that the answer was obvious: The most important change in the last 100 years has been the improvement in dental techniques.
He was joking, of course. But he was also right. If an archaeologist of the future digs up your body, he or she will know immediately that you lived in 2019, not 1919, simply by looking in your mouth. No one living before 1919 had teeth like the citizens of today's rich countries. Almost all adults had lost multiple teeth to accidents and cavities or by chewing fibrous foods full of gritty impurities that wore them down to stumps. One of my earliest memories, from the 1960s, is of scrutinizing my grandparents' dentures as they soaked in glasses of water. Before 1919, though, even dentures were the preserve of a lucky few.
Sitting in the dentist's chair, I was hardly going to argue with him, but it also occurred to me that if I put his comment into a slightly broader context, I did indeed have the subject for my speech in Kazakhstan. In the past 100 years, human bodies have changed more than they did in the previous 100,000 years. It is not your teeth alone that will allow the archaeologist of the future to put a date on your remains: Life expectancy at birth has risen by 30 years since 1919, average heights are up 10 centimeters and real per-person income has grown sixfold. And these are just the global averages. In much of Asia and Africa, the changes have been faster still. The corpses of the 21st century are different from those of any earlier age. We are literally not the same kinds of animals as our great-grandparents.
Medicine was one of the most important geopolitical forces of the 20th century, and it will remain so in the 21st. On the eve of World War I, British military recruiters were shocked to discover how unhealthy their troops were compared to Germans (let alone Americans, Canadians, Australians and New Zealanders). In our own age, though, the issues are rather different. Countries with good health care can extend the productive lives of their citizens, preserving human capital and improving the worker-dependent ratio. The graying of rich-world populations, as lifespans lengthen and fertility falls, need not be a negative — although the rich world will face formidable challenges in finding the upside.
Freed From Early Death
Through almost the whole of human history, life expectancy at birth was in the early 20s. Much of this was a result of high child mortality: Typically, roughly half the babies born would be dead five years later. Most of those who survived the great cull in their early years would live into their late 30s or early 40s, with men normally dying slightly younger than women. Such high mortality demanded high fertility rates, and most women would deliver between five and seven babies, spending the bulk of their adult lives bearing or minding small children. In highly unequal agricultural societies, small elites would eat well and grow tall and strong, but most people were stunted by malnutrition, with men averaging around 5 feet, 6 inches (1.68 meters) and women 5 feet, 2 inches (1.58 meters). Nearly everyone played host to disturbing numbers of parasites and put up with painful repetitive stress injuries. At Abu Hureyra in Syria, one of the world's earliest farming villages, excavated skeletons dating around 7000 B.C. reveal that both men and women had enlarged vertebrae in their upper backs, probably from carrying heavy loads on their heads. Most of the women, though, also suffered from a distinctive arthritic toe condition caused by spending long periods kneeling, using their toes as bases for applying force while grinding grain.
With just minor variations, this poor, nasty, brutish and short story held true everywhere until just three or four centuries ago. Only then did conditions change much, initially in Western Europe and its overseas settler colonies, and then (particularly since World War II) spreading around the globe. It is hard to disentangle the relative importance of different factors, but public health measures clearly played a part in this. Several centuries before governments learned to vaccinate their populations against measles and smallpox, they began collecting garbage and providing clean drinking water in cities. Their ability to quarantine entire towns was probably decisive in driving the plague from Western Europe during the 17th century. Higher expectations in personal hygiene made a difference too; wider availability of soap, the spread of easy-to-clean cotton underwear and eventually the installation of flushable toilets probably extended countless lives in the 18th and 19th centuries.
The most important contribution, though, probably came from more reliable food supplies. Weather-induced shortfalls in agricultural output continued, of course, but faster transport and more efficient markets steadily reduced the likelihood that local food shortages would turn into famines. England, for instance, has not known famine since 1597, and by the early 20th century, steamships and railroads were moving vast quantities of grain and livestock from highly productive regions in the American Midwest or the Argentine pampas to the cities of Western Europe and the American East Coast. The great famines of the 20th century — in Ukraine in the 1930s, Bengal in the 1940s, China in the 1960s or Ethiopia in the 1980s — owed more to governments' malice or incompetence than to the weather.
With more reliable food supplies making for sturdier adults, and machinery reducing wear and tear on people's bodies, average life spans increased almost everywhere during the 20th century.
More reliable food supplies did more than just reduce the risk of famine, though, because better-fed, bigger and healthier women could bear bigger and healthier babies, too, who stood a much better chance of surviving the everyday infections and diseases of infancy. In the United States, which led the way, roughly one baby in four still died before its first birthday even in the 1850s. By 1970 this figure had fallen to 1 baby in 50, and by 2014, it was just 1 in 163. The rest of the world has been catching up, particularly since 1945, and today, no fewer than 55 countries have rates even lower than the United States. In Japan, the safest big country for babies, just 1 infant in 400 dies in its first year.
Sturdier, better-fed adults proved more disease-resistant too, and grown-ups' average age at death leaped upward almost everywhere during the 20th century. The richest countries typically saw gains of 25-33 percent between 1900 and 1930 and another 25-33 percent between 1930 and 2000, producing average life spans close to 80 years. Russia, despite its horrific wars and totalitarian leadership, saw similar improvements between 1900 and 1930 but then added almost 50 percent more between 1930 and 1950. In 1880, the average Russian died 20 years before the average American, but by 1950 the gap was just five years. In China, the main improvements are more recent still. In 1950, the average Chinese person lived only about 40 years, roughly the length of an English life span a century earlier. By 2000, though, Chinese lives had increased by an astonishing 75 percent and were only seven years shorter than those in England.
Trends in morbidity paralleled those in mortality. According to the economic historian Robert Fogel, injuries and malnutrition combined to leave as many as one-fifth of 18th-century European men unfit to do manual labor. In the 19th and 20th centuries, the spread of machinery not only reduced the amount of manual labor that needed to be done but also cut wear and tear on people's bodies. For men, tractors, backhoes and pneumatic drills replaced plows, picks and shovels; for women, vacuum cleaners, piped water and washing machines replaced joint-destroying drudgery. Social historians rightly refer to these inventions as "engines of liberation," freeing us from injury and early death.
The graph below, showing the proportions of U.S. Army veterans who suffered from five different chronic conditions between 1910 and 1988, gives a sense of just how much has changed. (Given their line of work, veterans might not be the ideal subset for measuring health, but, thanks to compulsive military record-keeping, they provide the best multigenerational subset we have.) My grandfather, a steelworker who lived from 1906 to 1980, suffered from all of these conditions except for respiratory, but my father — who lived from 1929 to 2017, and began his career at 13 as a coal miner before escaping into engineering — only had heart disease. I very much hope the trend continues.
Further Improvements in Health
One reason for rich countries to worry that the trend might not continue is that they have already plucked all the low-hanging fruit in the 20th century. More can certainly be done to promote healthy diets and exercise, ensure access to clean water and reduce air pollution, but the gains will be smaller than those we have already seen. The United States also faces an unusual problem in the form of parents who refuse to vaccinate their children, but here too, the gains from correction will be small. Even though the number of unvaccinated children quadrupled between 2001 and 2016, it still stands at just 1.3 percent of the population.
Further major improvements in health are likely to come from just two sources — increasingly sophisticated (and expensive) medical procedures and wider access to high-quality care. All rich countries face serious challenges because medical costs are growing faster than their economies, but the United States faces further challenges. As the global leader in many kinds of health care, it is perhaps unsurprising that the United States has the highest health care costs per person, both in dollars spent ($9,536 per person in 2015, according to the World Health Organization, with Switzerland second, at $7,583) and as a proportion of gross domestic product (17 percent, with Switzerland again second, at 12.5 percent). However, the United States is also the only rich nation to lack universal coverage. The proportion of Americans under age 65 who have no health insurance fell from 14.8 percent in 2012 to 8.6 percent in 2016, but roughly 27 million people remain at risk. Solving these problems will be expensive and politically divisive.
The picture is very different in poor countries, where health spending remains minimal by Western standards. This means there is still plenty of low-hanging fruit in much of the world. South Africans, the biggest spenders in sub-Saharan Africa, invest on average only $1,086 in their health, while 17 other African countries allot less than $100 (the desperately poor Central African Republic manages only $32 per person). Even so, according to the World Bank, occurrences of diarrhea, lower respiratory infections and nutritional deficiencies all fell by 30-50 percent in sub-Saharan Africa between 1990 and 2010. Most countries also saw sharp falls in the likelihood of dying from malaria or AIDS, although declining mortality produced rising morbidity, with more work-years lost to sickness in 2010 than in 1990.
Health spending in poor countries remains minimal by Western standards. This means there is still plenty of low-hanging fruit in much of the world.
Nanotechnology, gene therapy and other revolutionary treatments will bring extraordinary benefits to the citizens of rich countries in the coming century. But if the marginal returns on health care spending keep falling, we should expect to see the huge 20th-century health gap between the West and the rest steadily closing. Despite already eroding so much of the gap between its life expectancy and the West's, China still ranks 94th in spending per person, at just $762. Chinese health care will be one of the 21st century's biggest growth areas.
High Tech, High Cost
My dentist was surely correct that improvements in health (including dentistry) were among the most important changes in the 20th century, and everything suggests that the same will be true in the 21st — but in a different way.
The West's 20th-century medical revolution allowed its citizens to live longer, feel better and work harder than those in other parts of the world, all of which contributed to its global economic, intellectual and military dominance. In the early 21st century, though, it seems unlikely that rich countries can squeeze much more out of the old, relatively cheap techniques of improving food supply, public health and hygiene. The next wave of Western breakthroughs will probably be high-tech, high-cost and perhaps available only to the rich. Wealthy elites in the rest of the world will doubtless continue flying to American and European hospitals to enjoy the same benefits, and a few hospitals in their home countries will probably emerge as competitors to the West's. The majority of Westerners, though, could well see the rate of improvement in their health slowing, even as a billion non-Westerners are lifted out of sickness, just as they have already been lifted out of poverty. The relative decline of the West will affect bodies as much as power and pocketbooks.