The Striking Statistics from a Century Ago
Around 1920, average life expectancy was remarkably different from modern figures. In the United States, for instance, life expectancy at birth was approximately 53.6 years for men and 54.6 years for women. These numbers, however, were heavily skewed by the high rate of infant and child mortality. For context, global average life expectancy in 1900 was a mere 32 years. This illustrates a key distinction: a person who survived childhood had a much higher chance of living a longer life than the average at-birth statistic would suggest. A century ago, the prospect of a long, healthy life was far from certain, particularly for the most vulnerable populations. The aftermath of the devastating 1918 influenza pandemic had a significant, though temporary, impact, with U.S. life expectancy dropping dramatically in 1918 before rebounding in 1919.
The Primary Culprits: Infectious Diseases of the 1920s
Many factors contributed to the shorter lifespans of a century ago, with infectious diseases being the most dominant. The causes of death statistics from the 1920s painted a clear picture. While today's leading causes are chronic conditions like heart disease and cancer, the top killers then were acute infectious ailments.
Leading causes of mortality included:
- Influenza and Pneumonia: These were frequent killers, often occurring as outbreaks. The 1918 pandemic, though receding by 1920, left a lasting impact on population health.
- Tuberculosis: This respiratory illness, also known as consumption, was a major public health menace, particularly in densely populated urban areas.
- Gastrointestinal Infections: Diseases like diarrhea and enteritis were deadly, especially for infants and children, and were often spread through contaminated food and water.
- Puerperal Sepsis: Childbirth was a high-risk event for women, with infections being a common and often fatal complication.
- Diphtheria and Whooping Cough: Vaccines for these and other childhood diseases were either not widely available or had only just been introduced, leading to high mortality rates among children.
Catalysts for Change: The Public Health Revolution
By the mid-20th century, the landscape of health and longevity began to shift dramatically. Several key advancements laid the groundwork for today's longer lifespans.
Key advancements included:
- Improved Sanitation: Large-scale public works projects provided access to clean drinking water and modern sewage systems, dramatically reducing waterborne diseases like cholera and typhoid.
- Vaccinations: The widespread development and distribution of vaccines for diseases such as diphtheria, whooping cough, and tetanus dramatically lowered childhood mortality rates.
- Medical Innovations: The discovery and initial use of insulin to treat diabetes and the later development of penicillin and other antibiotics were game-changers in treating previously fatal conditions.
- Better Nutrition and Living Standards: Rising real incomes and improved agricultural practices led to better nutrition, strengthening immune systems and increasing resilience against illness.
Understanding the Calculation of Life Expectancy
To truly understand the statistics from 100 years ago, it is important to know how life expectancy is calculated. Statisticians use what are called life tables to determine the average number of years a person can expect to live.
Two primary types of life expectancy exist:
- Period Life Expectancy: This is the most commonly cited figure. It measures the average lifespan of a hypothetical cohort if they were to experience the mortality rates of a specific period (e.g., a single year) throughout their lives. The average lifespan of 53.6 years for U.S. men in 1920 is a period life expectancy.
- Cohort Life Expectancy: This tracks an actual group of people born in the same year and calculates their average age at death. This is only possible after all members of the cohort have passed away.
It is crucial to understand that a low life expectancy at birth a century ago didn't mean that a person who reached adulthood would die young. Rather, it meant that a significant portion of the population didn't survive early childhood, pulling the overall average down.
A Comparative Look: Wealth Disparities and Longevity
Life expectancy a century ago was not uniform across the globe; it was heavily influenced by economic development and wealth. In 1900, a stark health divide existed, with Europe, North America, and Oceania having significantly higher life expectancies than most of Asia and Africa. In 1950, for example, Norway led with a life expectancy of 72 years, while Mali's was only 26 years. These disparities highlight how access to public health interventions, medicine, and sanitation disproportionately impacted longevity in different regions.
Comparing Longevity: 1920 vs. Today
| Feature | Average Life Expectancy (U.S.) in ~1920 | Average Life Expectancy (U.S.) Today | Key Change |
|---|---|---|---|
| At Birth | ~54 years | ~77 years (2022 provisional) | A more than 20-year increase |
| Leading Causes of Death | Influenza, Pneumonia, Tuberculosis | Heart Disease, Cancer | Shift from infectious to chronic diseases |
| Infant Mortality | High, significantly impacting average lifespan | Very low compared to a century ago | Improved prenatal care and sanitation |
| Healthcare Access | Limited, especially for advanced treatments | Widespread access to advanced medical care | Increased access to vaccinations, antibiotics |
| Public Health | Emerging practices, just starting to see impact | Established infrastructure, sanitation, disease control | Massive investment in public health |
Conclusion: A Century of Progress and the Future of Aging
The dramatic increase in life expectancy over the last 100 years is one of humanity's greatest achievements. It was not a single event but the culmination of medical discoveries, public health initiatives, and economic progress. For healthy aging and senior care today, this history serves as a powerful reminder of how far we've come. The modern challenges are different—managing chronic diseases and fostering mental and physical wellness in older age—but the foundation of a longer life was built on the hard-won lessons of the past. To explore more about the history of longevity and other global health trends, visit Our World in Data on Life Expectancy.
