What are the main reasons that life expectancy has increased?

September 29, 2025 •

3 min read

The global average life expectancy has more than doubled since the 19th century, rising from roughly 30 years to over 70 years today. This monumental shift raises the question, "What are the main reasons that life expectancy has increased?" It's a testament to monumental advances in multiple fields, not just a single cause.

Quick Summary

Life expectancy has increased due to significant improvements in public health and sanitation, major medical advancements like vaccines and antibiotics, better nutrition, and socioeconomic development leading to healthier lifestyles.

Key Points

Public Health is Primary: Early gains in life expectancy were largely driven by public health initiatives like improved sanitation and widespread vaccination, which curbed infectious diseases.
Medical Advances are Key: The development of antibiotics, advanced diagnostics (like MRI), and better treatments for chronic diseases (heart disease, cancer) have been crucial in extending life, especially for older adults.
Socioeconomic Factors Matter: Better nutrition, economic stability, and increased education levels have all contributed to healthier populations and longer lifespans [1.4].
Shift in Health Challenges: The focus of health has shifted from combating infectious diseases in younger populations to managing chronic, age-related illnesses in an older population [1.4].
Multiple Factors at Play: The increase in longevity is not due to a single cause but a combination of public health, medical, and socioeconomic developments over several centuries.

The Foundational Role of Public Health and Infrastructure

Early increases in life expectancy were significantly driven by improvements in public health rather than individual medical treatments. These advances focused on tackling infectious diseases, which were the primary cause of death, particularly among infants and children.

Advancements in Sanitation and Hygiene

The implementation of modern sanitation systems, including the provision of clean water and effective sewage disposal, drastically reduced the spread of waterborne diseases like cholera and typhoid. Understanding and adopting better personal hygiene practices, such as handwashing, also played a crucial role in preventing infection [1.3].

The Impact of Widespread Vaccination

Vaccines represent a major public health triumph, preventing millions of deaths from diseases like smallpox, polio, and measles [1]. The Centers for Disease Control and Prevention recognizes vaccination as one of the 20th century's most impactful public health achievements for its role in extending life and improving health [1]. Find more information on the CDC website.

Medical and Scientific Breakthroughs

Over the 20th and 21st centuries, significant progress in medicine has allowed for the treatment and management of conditions previously considered fatal [1.4].

The Discovery and Use of Antibiotics

The advent of antibiotics in the 1940s provided a powerful tool against bacterial infections [1]. This not only saved lives from conditions like pneumonia but also made surgical procedures and injury management much safer, contributing to increased lifespans [1].

Advanced Diagnostics and Chronic Disease Management

With people living longer, the focus shifted to chronic conditions associated with aging, such as heart disease and cancer [1]. Improved diagnostic technologies, combined with advanced treatments for these conditions, have been instrumental in further extending life expectancy, particularly for older individuals.

Socioeconomic Development and Lifestyle Changes

Economic growth, increased access to education, and shifts in societal behaviors have created conditions that support longer lives [1.4].

Improved Nutrition and Food Security

Advances in food production and distribution have led to better nutrition and greater food security for many populations [1]. Healthier diets have reduced deficiency diseases and bolstered immune systems [1].

Education and Health Literacy

Higher education levels are linked to longer life expectancy [1.4]. Educated individuals tend to be more aware of health risks, adopt healthier lifestyles, and seek preventive care, contributing to better long-term health outcomes [1].

Comparison of Factors Influencing Life Expectancy


Factor	Impact: 19th Century	Impact: 21st Century
Infectious Diseases	Primary cause of death, especially for children.	Largely controlled through vaccination and sanitation.
Chronic Diseases	Limited impact due to shorter lifespans.	Primary cause of death, managed with advanced medicine.
Sanitation	Poor infrastructure led to widespread contamination.	Modern systems minimize exposure to pathogens.
Medical Intervention	Primarily rudimentary, focused on acute care.	Advanced diagnostics, drugs, and surgery dominate.
Nutrition	Often inconsistent, with deficiency diseases common.	Generally stable, though diet-related issues like obesity are concerns.
Public Health Initiatives	Developing and rudimentary efforts.	Comprehensive and systemic; a major driver of health.

Conclusion: A Multifaceted Legacy

The increase in life expectancy is the result of multiple factors that have evolved over time [1.4]. While initial improvements were driven by public health measures reducing infectious diseases, more recent gains are linked to medical advancements managing chronic conditions. This cumulative progress, supported by socioeconomic development, has significantly transformed human longevity [1.4]. However, new health challenges continue to arise, highlighting the ongoing importance of public health efforts [1].

Frequently Asked Questions

Improvements in sanitation, such as providing clean drinking water and effective waste disposal, drastically reduced the spread of infectious diseases like cholera and typhoid. These diseases were major killers, especially in infants and young children, so controlling them had a massive impact on overall life expectancy.

Vaccines played a monumental role by preventing or eradicating deadly and debilitating diseases that once caused high mortality rates [1]. Diseases like smallpox, polio, and measles were largely eliminated, allowing more children to survive into adulthood and contributing significantly to longer average lifespans [1].

While medical innovations are critical, they are not the sole or even the initial most important factor. Early increases were due more to public health measures like sanitation. However, modern medical advances, particularly in managing chronic diseases, have been essential for continuing to increase life expectancy, especially at older ages.

Socioeconomic factors are closely tied to health outcomes. Higher education often leads to higher health literacy, better lifestyle choices, and more stable, safer jobs [1.4]. Economic stability also ensures better access to healthcare and nutritious food, all of which support a longer, healthier life [1.4].

Life expectancy can be affected by major events or specific health crises. Examples include wars, pandemics (like the 1918 flu or COVID-19), and epidemics of specific issues such as drug overdoses or lifestyle-related chronic diseases. These events can cause significant, though often temporary, setbacks in longevity trends.

Increasing life expectancy means people are simply living longer. Compressing morbidity refers to the idea that the period of illness and disability at the end of life can be shortened. Ideally, people would live longer, healthier lives and then experience a shorter period of decline before death.

No, gains in life expectancy are not universal. Significant disparities exist, often linked to socioeconomic status, geographic location, and racial/ethnic background. Public health efforts and equitable access to healthcare remain crucial for ensuring that increases in life expectancy benefit all segments of society.