The Longevity Revolution

Life through much of human history was indeed brutish and short—humans lived barely long enough to reproduce themselves. For the mere survival of the human race, a proportion of individuals had to live long enough to give birth and rear their young (Figure 1.1). Yet, it is sobering to note that, according to archeological estimates, half of all Neanderthals (the archetypal caveman living one hundred thousand to thirty-five thousand years ago) and Upper Paleolithic homo sapiens (beginning forty thousand years ago and including Cro-Magnon man) died by the time they were twenty, with only a few living beyond age fifty.

The Cro-Magnon era brought longer life expectancy for some, with the rare individual living beyond age sixty. This fledgling longevity, sporadic as it was, became possible as humans began to work together to create a better standard of living. Although they were less muscular, Cro-Magnons eventually replaced the intellectually outpaced Neanderthals. However, like their predecessors, the vast majority of Cro-Magnons continued to die at an average age of eighteen to twenty.

Before I continue, it is important to define the terms life expectancy and life span and distinguish between them. Life expectancy is based on the average number of years that each sex can expect to live, under specific conditions. Life span is the genetically determined length of life of a specific animal species under the best of environmental circumstances. It probably increased during early hominid development but has not, in all likelihood, increased since that time. Life expectancy is more malleable and is dependent upon a variety of factors that can change quickly, such as the conquest of diseases. For example, between 1900 and 2000, life expectancy in the United States increased over thirty years.¹

Although early humans had bodily defenses, their immunities were probably specific to local pathogens, so when our forebears traveled they were exposed to new infectious diseases to which they lacked immunity. Illness was largely a mystery to be accounted for by spirits, gods, evil, and retribution, or, as Euripides wrote in Medea, “A throw of chance—and there goes Death bearing off your child into the unknown.” Nature or the gods were blamed for accidents, plagues, pestilence, famine, and even wars.

The prospects for health and survival brightened a bit as hunting, fishing, and food gathering progressed to include the cultivation of plants and the domestication of animals during the Neolithic era. The Fertile Crescent was the site of the first technology essential to public health. Reliable fire-making techniques made cooked food and heated water possible. The development of pottery in the Neolithic period advanced more hygienic and convenient storage of food and water and the disposal of waste and garbage. Permanent population sites became common, and the overall number of human beings greatly increased. Nonetheless, the length of life that could be expected by any individual changed little, even though many more people were alive.

The Bronze Age opened the door to the first real improvements in human longevity, such as the manufacture of metal tools and weapons made of bronze, the rise of urbanization, the specialization of labor, the exploration and colonization of new territories in search of raw materials, and undoubtedly the production of surplus food. These developments provided the social and environmental supports for increases in life expectancy. The Iron Age (around 1200 BC) continued the trend toward permanent settlements, laying the foundation for social organization and advancing agriculture through the use of iron implements.

Imperial Rome at its height brought a relatively high standard of living and health to its more than one million inhabitants. Life expectancy was twenty-five years; however, it is important to note that this number includes a very high infant mortality rate. Those who survived beyond childhood had an average life expectancy of forty.² But by AD 180 Roman culture began its decline, and nothing remotely like it appeared again until the eighteenth and nineteenth centuries in Europe. Scholars believe there was a dip in life expectancy after the decline of the empire.

As humankind moved from prehistory to the early modern era of Western civilization,³ life continued to be fragile. Infant and childhood mortality and the random and frequent deaths of adults—especially of women during childbirth—from infections, disease, and accidents were the norm. These commonplace and expectable deaths were punctuated by the devastations of plagues, failed harvests, famines, and scourges like scurvy and beriberi that seemingly sprang from nowhere. Typically, epidemics broke out as people became so weakened by hunger and malnutrition that they were predisposed to disease.

Although plague was first recorded in Athens in 430 BC, and five thousand died daily in Rome in an epidemic in the third century AD, the most infamous plague occurred in the late Middle Ages. The Black Death, as the bubonic form of the plague was known, began in Constantinople in 1334 and spread throughout Europe from 1348 until 1351. In fewer than twenty years, it is estimated to have killed perhaps three-quarters of the population of Europe and Asia.

It was not until Shibasaburo Kitasato and Alexander Yersin discovered the plague bacterium in 1894 that it became clear that the disease was carried by fleas from rats to humans and proliferated in dirty, garbage-strewn living situations. Plague continued into the nineteenth century in Europe; the last was in India in the early twentieth century, resulting in ten million deaths.

Epidemics continued into the twentieth century. Tuberculosis, known variously as consumption or the white plague, was particularly rampant and deadly. As late as 1930, eighty-eight thousand people in the United States died of tuberculosis. Although Robert Koch, a German physician and bacteriologist, discovered the tubercle bacillus in 1882, the disease was not controlled until the 1940s when streptomycin and other drugs became available.

Many scholars consider smallpox to have been more significant in its effect on populations and political developments than even the Black Death, because it struck all classes of society. Edward Jenner, an English physician, demonstrated how it could be prevented by a vaccination with cowpox virus. His discovery laid the foundation for the sciences of modern immunology and virology as well as the eventual elimination of smallpox. The last outbreak occurred in the 1970s in Somalia, where it was quickly suppressed. In May 1980 the World Health Organization officially declared its global eradication, marking perhaps the world’s greatest public health achievement. Smallpox, a scourge throughout history, is now extinct in nature.

Polio could be the second disease of epidemic proportions to become extinct worldwide. As with smallpox, humans are its only known natural host. During its peak, from 1943 to 1956, polio infected some four hundred thousand Americans and killed about twenty-two thousand. The disease began to decline rapidly in the United States in 1955, after a mass immunization program with the Salk vaccine, followed by the Sabin vaccine in 1961.

Influenza, an old enemy, made its most spectacular showing between 1917 and 1919, killing at least twenty-one million worldwide and infecting half the world’s population. Twice as many people perished in a few months’ time as had been killed in World War I, with people dying faster than from any other disease. Half a million died in the United States. Eventually, the pandemic ended, probably because most survivors developed antibodies, producing what might be called a herd immunity and leaving few people for the virus to attack.

In assessing the impact of disease over the centuries, or even over the first half of the twentieth century, it is important to remember that death was not the only consequence. Permanent disability was widespread in children who survived the so-called children’s diseases, such as whooping cough and German measles, and disability hastened death. In addition to the physical trauma, one can only imagine the emotional anxiety and fear that families felt, especially for their children, when diseases of mysterious origin, and for which no treatment was known, struck at random or with chilling predictability during epidemics. The life of a child was precarious; that of an adult only somewhat less so.

Nonetheless, the Industrial Revolution and the wealth it generated brought significant increases in longevity.⁴ Beginning in the middle of the eighteenth century in England, Europe was transformed from a rural, agricultural, and handicraft economy to one dominated by mass production of manufactured goods, improved agriculture, and wider distribution. It became possible to feed a much larger population, many of whom were now working in urban areas. The significance of this transformation cannot be overstated. Robert Fogel, economist and Nobel Prize winner, estimates that prior to the Industrial Revolution in France and England, about one-fifth of working class people had a calorie intake that was inadequate to sustain them and that during the eighteenth and even the nineteenth century there was widespread and chronic malnutrition.⁵ Fogel notes that the increase of longevity and stature⁶ over the past two hundred years was due to the availability of more food, and he introduced the concept of “technophysio evolution” to describe these changes.⁷

In response to epidemics of yellow fever, cholera, smallpox, typhoid, and typhus, communities began to recognize the benefits of organized efforts to address health issues. Predating the germ theory of disease, social reformers, motivated by moral concern, contributed critically to public health measures.⁸ In 1866, New York created the first state health department, with local boards in each town mandated to monitor serious health problems and attend to unsanitary living conditions. Other states followed, and organized public health efforts began.

Another element that contributed to the Longevity Revolution really began in the bedrooms of Europe (first, notably, in France) in the nineteenth century, when couples started to limit the number of children they conceived by purposefully abstaining from sexual intercourse in order to save the women from dying in childbirth. The resulting decline in birthrates produced two very important changes: the proportion of older persons and other age groups in the population increased and the longer time between births as well as fewer pregnancies per woman contributed to increased health and survival of both infants and mothers.

Meanwhile, by the beginning of the nineteenth century, another major element of the Longevity Revolution was taking shape, namely a revolution in medical science. In 1846, the general structure of the human body was almost fully known when an American surgeon, William Morton, opened the way to the field of surgery by using ether as a general anesthetic. At the same time, it was becoming clear that specific organisms caused infections. John Snow, a physician, unraveled the basis of contagion when he demonstrated that contaminated water flowing through a Broad Street pump was the cause of the 1866 London cholera epidemic. Subsequent improvements in water supply and sewage systems reduced both water-borne and food-borne diseases.

The real breakthrough came in the late nineteenth century when Louis Pasteur and Robert Koch developed and demonstrated the germ theory of disease, beginning a dramatic decline in death rates. With this discovery, health professionals and the general public finally understood how some diseases and infections were communicated. The work of Pasteur, a French chemist, led directly to pasteurization and the protection of millions of children and adults from disease transmitted through milk. At about the same time, Koch developed ingenious techniques for the study of bacteria that are still in use today. He established criteria, referred to as Koch’s postulates, for proving the bacterial cause of a disease. In the process he discovered the microorganism causing tuberculosis as well as those causing wound infections and Asiatic cholera.

By the end of the nineteenth century, proof of the germ theory of disease began to transform medical care and hospital practices. Decades earlier, Hungarian physician Ignaz Semmelweiss was driven to insanity and suicide after his peers ridiculed his pioneering belief that midwives and other medical personnel delivering babies should thoroughly wash their hands and wear clean clothes to prevent “childbirth fever” (puerperal fever),⁹ a major cause of death among women giving birth. Skep-tics were unconvinced even by the evidence of greatly reduced deaths from infection in the Viennese hospital where Semmelweiss worked.¹⁰ In 1865, the very year of Semmelweiss’s death, English surgeon Joseph Lister demonstrated that heat sterilization of surgical instruments and the use of antiseptic agents on wounds could dramatically reduce infection. Cleanliness during childbirth and in medical care in general was adopted by the 1890s, unfortunately too late for Semmelweiss to know that he had been vindicated.

The developing science of endocrinology, the study of the body’s hormonal system, also brought dramatic changes, exemplified by the important discovery of insulin by Frederick Banting and Charles Best, both Canadians, in 1921. Practically overnight, diabetics were saved from almost certain death and given the prospect of reasonably long and healthy lives.

Other drug discoveries led to seemingly miraculous cures, and Alexander Fleming’s discovery of penicillin in 1928 was perhaps the most dramatic of all. Prior to penicillin, even minor cuts and bruises could have dire consequences. Many Americans past the age of sixty still clearly recall the days of childhood ear infections and other miseries that quickly became curable when penicillin came into general use in the 1940s. Young military personnel in World War II were among the first to benefit from its lifesaving effects.