Life expectancy (LE) is intuitively defined by the number of years an individual is expected to live. For the purposes of this article, I mean life expectancy at birth – the number of years a newborn infant is expected to live with prevailing patterns of mortality. This is an important distinction as crude measures of LE are subject to bias based on the rates of mortality at childbirth. Perhaps Unsurprisingly, life expectancy has varied significantly through time. Even accounting for the same period however, individuals living in different countries can vary significantly in their life expectancies. We will explore some of these differences in this infographic.
Variations in life expectancy through time
Strikingly, world average LE from the paleolithic era (2.6 million – 10,000 BC) up until the 1950s remained fairly stagnant – varying from 20 – 50 years, with individuals rarely surpassing 50 years of age. Take Europe as an example: throughout the 19th century, the United Kingdom regularly boasted the world’s highest LE, at 42 years in the 1840s and 46 years in the 1890s. Little more than half a century later, in the 1950s, implementation of public health measures like mass vaccination campaigns and antibiotic use would skyrocket the world LE to 48 years, with European average being 60 years, and the world leader, Norway, reaching 72 years. Today, the global LE is 73 years, with Hong Kong leading the world at over 85 years.
- Alexander Fleming discovered the first antibiotic – Penicillin – in 1928. It is thought that antibiotics have increased overall life expectancy by up to 20 years.
- Vaccination campaigns have decreased total infant mortality by more than 40%.
- In the United States, the LE between 1900 – 1999 increased by 30 years, of which 25 years can be attributed to advances in public health.
- Recently, East Asian countries such as Japan and Hong Kong have surpassed those in Europe in LE due to decreased rates of cerebrovascular disease resulting from decreased obesity and dietary intake of red meat and sodium.
Regional variation in life expectancy
The rapid increase in LE among developed nations occurred in stark contrast to regions like sub-Saharan Africa, where LE remains relatively low at 61 years. Unfortunately, the low LE of African nations relative to leading nations is due to a multitude of factors, not the least of which are factors concerning public health and infectious disease. For example, HIV/AIDS has been – and continues to be – a public health concern in the region, and at the height of its spread in the late 20th century, had decreased the LE of sub-Saharan Africans from 64 to 47 years. Fortunately, the development of antiretroviral therapy to treat HIV/AIDS has led to a rebound in LE in this region to its current 61 years.
Apart from sub-Saharan Africa, other (albeit smaller) sub-regional variations exist in LE across the globe. For example, on average, Eastern Europeans tend to live shorter lives than their Western European counterparts by up to 10 years. The overall LE for Eastern Europe at 74 years is comparable to South America, where the average person can expect to live until 76. Such regional differences are caused by numerous factors including the quality of healthcare, socioeconomic status, and diet.
- In Botswana – one of Africa’s wealthiest countries by GDP per capita – the life expectancy in the 1990s was 65 years, but plummeted to 36 years by 2002 due to HIV/AIDS.
- The heritability of lifespan is estimated to be less than 10% highlighting the importance of environment on LE.
The remarkable increases in life expectancy over the past century underscore the profound impact of scientific advancements on human survival. From the discovery of antibiotics and the advent of vaccines to public health initiatives and disease management strategies, science has fundamentally transformed the trajectory of global health. However, regional variations in LE still exist, which highlights an urgent need for investment into healthcare infrastructure in regions with low LE. Nonetheless, continued investment in research and innovation offers promising opportunities to reduce disparities and improve lifespans worldwide.
References:
- Life expectancy at birth. OECD https://www.oecd.org/en/data/indicators/life-expectancy-at-birth.html.
- Dattani, S., Rodés-Guirao, L., Ritchie, H., Ortiz-Ospina, E. & Roser, M. Life Expectancy. Our World in Data (2023).
- Life expectancy. Wikipedia (2024).
- United Kingdom: life expectancy 1765-2020. Statista https://www.statista.com/statistics/1040159/life-expectancy-united-kingdom-all-time/.
- Life Expectancy by Country and in the World (2024) – Worldometer. https://www.worldometers.info/demographics/life-expectancy/.
- What would happen if antibiotics stopped working? | ANTRUK. Antibiotic Research UK https://www.antibioticresearch.org.uk/happen-antibiotics-stopped-working/ (2018).
- Vaccines accounted for 40% of the decline in infant mortality over the last 50 years. Our World in Data https://ourworldindata.org/data-insights/vaccines-account-for-40-of-the-decline-in-infant-mortality-over-the-last-50-years.
- Ten Great Public Health Achievements — United States, 1900-1999. https://www.cdc.gov/mmwr/preview/mmwrhtml/00056796.htm.
- Tsugane, S. Why has Japan become the world’s most long-lived country: insights from a food and nutrition perspective. Eur J Clin Nutr 75, 921–928 (2021).
- HIV progress raises life expectancy in Africa – UN. https://www.gavi.org/vaccineswork/hiv-progress-raises-life-expectancy-africa-un.
- Health statistics in the Western Pacific Region 2023: Monitoring health for the SDGs – Australia | ReliefWeb. https://reliefweb.int/report/australia/health-statistics-western-pacific-region-2023-monitoring-health-sdgs (2024).
- AIDS cuts life expectancy insub-Saharan Africa by a quarter | The BMJ. https://www.bmj.com/content/319/7213/806.1.
- Why life expectancy is lower in eastern Europe. https://www.economist.com/europe/2018/09/20/why-life-expectancy-is-lower-in-eastern-europe.
- South America Life Expectancy 1950-2024. https://www.macrotrends.net/global-metrics/countries/NAC/south-america/life-expectancy.
- Botswana’s Program for Preventing Mother-to-Child HIV Transmission. (2011).
- Ruby, J. G. et al. Estimates of the Heritability of Human Longevity Are Substantially Inflated due to Assortative Mating. Genetics 210, 1109–1124 (2018).
Boyan Tsankov
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