There are, it must be said, problems with life expectancy figures. All death lists are in some measure arbitrary, particularly with respect to the elderly, who may have lots of debilitating conditions, any one of which may finish them off and all of which are bound to contribute. In 1993, two American epidemiologists, William Foege and Michael McGinnis, wrote a famous paper for The Journal of the American Medical Association arguing that the leading causes of death recorded on mortality tables—heart attacks, diabetes, cancer, and so on—were very often outcomes of other conditions and that the real causes were factors like smoking, poor diet, illicit use of drugs, and other behaviors overlooked on death certificates.
A separate problem is that deaths in the past were often recorded in strikingly vague and imaginative terms. When the writer and traveler George Borrow died in England in 1881, to cite one example, the cause of death was listed as “decay of nature.” Who can say what that might have been? Others were recorded as being carried off by “nervous fevers,” “stagnation of the fluids,” “sore teeth,” and “fright,” among many other causes of a wholly uncertain nature. Such ambiguous terms make it nearly impossible to produce reliable comparisons between causes of death now and in the past. Even for the two lists above, there is no telling how much correspondence may exist between senility in 1900 and Alzheimer’s disease today.
It is also important to bear in mind that historic life expectancy figures were always skewed by childhood deaths. When we read that life expectancy was forty-six years for American men in 1900, that doesn’t mean that most men got to forty-six and then keeled over. Life expectancies were short because so many children died in infancy, and that dragged the average down for everyone. If you got past childhood, the chances of living to a reasonably advanced age weren’t bad. Lots of people died early, but it was by no means a cause of wonder when people lived into old age. As the American academic Marlene Zuk has put it, “Old age is not a recent invention, but its commonness is.” The most heartening advance of recent times, however, is the striking improvement in mortality rates for the very young. In 1950, 216 children in every thousand—nearly a quarter—died before the age of five. Today the figure is just 38.9 early childhood deaths in a thousand—one-fifth what it was seventy years ago.
Even allowing for all the uncertainties, there is no question that early in the twentieth century people in the developed world began to enjoy much better prospects for living longer lives in better health. As the Harvard physiologist Lawrence Henderson famously remarked, “At some point between 1900 and 1912, a random patient with a random disease, consulting a doctor chosen at random, had for the first time in history a better than fifty-fifty chance of profiting from the encounter.” The more or less universal consensus among historians and academics was that medical science somehow turned a corner when it entered the twentieth century and just kept getting better and better as the century progressed.
Any number of reasons have been proposed for the improvement. The rise of penicillin and other antibiotics like Albert Schatz’s streptomycin had an obvious and significant impact on infectious diseases, but other medicines flooded the market, too, as the century proceeded. By 1950, half of the medicines available for prescription had been invented or discovered in just the previous ten years. Another huge boost can be attributed to vaccines. In 1921, America had about 200,000 cases of diphtheria; by the early 1980s, with vaccination, that had fallen to just 3. In roughly the same period, whooping cough and measles infections fell from about 1.1 million cases a year to just 1,500. Before vaccines, 20,000 Americans a year got polio. By the 1980s, that had dropped to 7 a year. According to the British Nobel laureate Max Perutz, vaccinations might have saved more lives in the twentieth century even than antibiotics.
The one thing no one doubted was that practically all the credit for the great advances lay securely with medical science. But then, in the early 1960s, a British epidemiologist named Thomas McKeown (1912–88) looked at the records again and noted some curious anomalies. Deaths from a large number of maladies—tuberculosis, whooping cough, measles, and scarlet fever notably—had begun to decline well before effective treatments had become available. Tuberculosis deaths in Britain dropped from four thousand per million in 1828 to twelve hundred in 1900, and to just eight hundred per million in 1925—a fall of 80 percent in a century. Medicine could account for none of that. Childhood scarlet fever deaths went from twenty-three per ten thousand in 1865 to just one per ten thousand in 1935, again without vaccines or other effective medical interventions. All told, McKeown suggested, medicine could account for no more than perhaps 20 percent of the improvements. All the rest were the result of improved sanitation and diet, healthier lifestyles, and even things like the rise of the railways, which improved food distribution, bringing fresher meat and vegetables to city dwellers.
McKeown’s thesis attracted a good deal of criticism. Opponents maintained that McKeown was carefully selective in the diseases he used to illustrate his thesis and that he underplayed the role of improved medical care. Max Perutz, one of his critics, argued persuasively that hygiene standards in the nineteenth century hadn’t advanced at all, but were continually eroded by the hordes of people crowding into newly industrializing cities and living in squalid conditions. The quality of drinking water in New York City, for one, declined steadily, and dangerously, in the nineteenth century—so much so that by 1900 residents of Manhattan were being instructed to boil all water before using it. The city didn’t get its first filtration plant until just before World War I. It was the same in almost every other major urban area in America as growth outpaced municipalities’ abilities or willingness to provide safe water and efficient sewerage.
However we decide to apportion the credit for our improved life spans, the bottom line is that nearly all of us are better able today to resist the contagions and afflictions that commonly sickened our great-grandparents, while having massively better medical care to call on when we need it. In short, we have never had it so good.
Or at least we have never had it so good if we are reasonably well-off. If there is one thing that should alarm and concern us today, it is how unequally the benefits of the last century have been shared. British life expectancies might have soared overall, but as John Lanchester noted in an essay in the London Review of Books in 2017, males in the East End of Glasgow today have a life expectancy of just fifty-four years—nine years less than a man in India. In exactly the same way, a thirty-year-old black male in Harlem, New York, is at much greater risk of dying than a thirty-year-old male Bangladeshi—and not, as you might think, from drugs or street violence but from stroke, heart disease, cancer, or diabetes.
Climb aboard a bus or subway train in almost any large city in the Western world and you can experience similar vast disparities with a short journey. In Paris, travel five stops on the Metro’s B line from Port-Royal to La Plaine—Stade de France and you will find yourself among people who have an 82 percent greater chance of dying in a given year than those just down the line. In London, life expectancy drops reliably by one year for every two stops traveled eastward from Westminster on the District Line of the Underground. In St. Louis, Missouri, make a twenty-minute drive from prosperous Clayton to the inner-city Jeff-Vander-Lou neighborhood and life expectancy drops by one year for every minute of the journey, a little over two years for every mile.