Ancient Times

In ancient civilizations — including Mesopotamia, Egypt, Greece, Rome, China, and India — life expectancy typically ranged from about 30 to 35 years at birth. As in earlier eras, the biggest factor was high infant and child mortality, with around a quarter to half of children dying before adulthood. Infectious diseases such as malaria, tuberculosis, dysentery, and smallpox were widespread, and cities often magnified these dangers through crowding, poor sanitation, and contaminated water.

Yet surviving childhood changed the picture dramatically. In ancient Rome, for example, someone who reached adolescence often had a realistic chance of living into middle age, and some reached their 60s, 70s, and beyond. Geography also mattered, with rural populations sometimes faring slightly better than urban dwellers because lower population density reduced exposure to recurring epidemics and unsanitary conditions.

Middle Ages

From roughly the sixth century to the 16th century, life expectancy at birth in much of medieval Europe generally remained around 30 to 35 years, though estimates varied widely by region, social class, and century. The numbers were likely comparable in parts of Asia and the Middle East, where high infant mortality, infectious disease, and periodic crises such as famine kept life expectancy at birth relatively low, though surviving demographic data for these regions is less complete than for Europe. 

Across the long period of the Middle Ages, repeated crises — including wars, famines, and epidemic disease outbreaks — caused mortality to fluctuate sharply from one decade to the next. The most devastating of these was the Black Death, which killed tens of millions of people and is estimated to have reduced Europe’s population by around 30% to 50%. During such catastrophes, life expectancy could collapse temporarily. Outside crisis years, however, the broader pattern still resembled earlier centuries with very high infant mortality and a reasonable chance of reaching your 50s if the dangerous early years were survived.

1600s

By the 17th century, global life expectancy still hovered around 30 to 35 years. In Europe and parts of Asia, expanding trade networks connected populations more than ever before, but they also accelerated the spread of disease. Growing cities were especially dangerous, with overcrowding, poor sanitation, and repeated outbreaks of plague, smallpox, and typhus.

At the same time, the intellectual foundations of modern science were beginning to emerge. Early anatomical studies, better recordkeeping, and more systematic observation started to challenge inherited medical beliefs. These developments did not yet transform everyday survival, but they laid the groundwork for the major public health and medical advances that followed in later centuries.

1700s

During the 18th century, life expectancy at birth in parts of Western Europe slowly rose from the mid-30s to around 40 years by the century’s end. Gradual improvements in agriculture increased food availability and reduced famine, while early public health measures — though unevenly applied — helped conditions in urban populations.

One of the most important breakthroughs was the spread of smallpox inoculation, which reduced deaths from one of the era’s most feared diseases. Even so, progress remained fragile, with infant mortality still often 30% to 40% or higher, and infectious diseases continued to define the limits of human lifespan.

1800s

The 19th century marked a major turning point in longevity, especially in industrializing countries such as Britain and the United States. Life expectancy rose from roughly 35 to 40 years at the century’s start to around 45 to 50 years by the end. Although industrial cities initially produced terrible living conditions, they also became the testing ground for major reforms.

The biggest gains came less from direct medical treatment than from public health infrastructure. Sewage systems, clean water supplies, waste removal, and better urban sanitation sharply reduced deaths from cholera, typhoid, and other waterborne diseases. Improved transportation and agricultural productivity also strengthened nutrition, while germ theory fundamentally changed scientific understanding of disease and set the stage for modern medicine.

1900s

The 20th century saw the most dramatic gains in life expectancy in all of human history. Around 1900, global life expectancy was about 32 years, though it was higher  in parts of Europe and North America at roughly 45 to 50 years. Over the next hundred years, however, survival improved not only for children but across every age group; by the late 20th century, global life expectancy had climbed to roughly 65 years.

Vaccines sharply reduced deaths from diseases such as measles, diphtheria, and polio, while antibiotics beginning with penicillin made many once-fatal infections treatable. Advances in surgery, maternal care, neonatal medicine, and medical imaging further improved outcomes. Just as important were cleaner water, safer food systems, improved housing, better working conditions, and stronger nutrition. 

2000s to Today

In the 21st century, life expectancy has continued to rise globally, though the pace has slowed in some regions. By the early 2020s, the global average was roughly 71 to 73 years, more than double the global average at the start of the 20th century.

The differences between countries, however, are striking. Nations such as Japan, Switzerland, and Singapore exceed 83 to 84 years, while some lower-income countries — particularly in sub-Saharan Africa — remain in the 60s or below because of limited health care access, infectious disease burdens, and persistent inequality. Recent events have also shown that progress is not guaranteed. The COVID-19 pandemic caused temporary declines in life expectancy in many countries in 2020 and 2021, a reminder that even one of humanity’s greatest success stories can still reverse.