Aaron O'Neill
Research expert covering historical data
One of humanity’s crowning achievements of the past 250 years is the drastic increase in life expectancy. In pre-industrial times, average life expectancy from birth was around 24 years, but today, the figure is approximately 74 years. This 50-year increase has come about in several ways, and at different rates across the globe. However, there is still a 33-year gap between the countries with the highest and lowest life expectancies, Monaco (87) and Chad (54) respectively, and these figures widen further when factors such as gender, location, and income are taken into account, showing there is much progress to be made.
The figure of 24 years may also paint a misleading picture of age-composition across pre-industrial societies. Infant and child mortality was so high that a quarter of babies didn’t make it to their first birthday, and another quarter didn’t survive until adulthood, but those who survived adolescence could expect to live well into their 50s or 60s. Yet, life expectancy among older groups was still much lower than today, as medical knowledge and technology was not advanced enough to deal with additional factors such as surgeries, infections, chronic and degenerative diseases, among many others.
However, the reduction in child mortality is not the only driver of increased life expectancy, as humanity has also got better at keeping adults alive, and many groundbreaking medical advances have had more impact on the adult population. For example, the discovery of antibiotics in 1928 has greatly reduced the danger of many injuries and surgeries, as has modern anesthesia since the mid-1800s. The development of medical imaging technology since x-ray’s discovery in 1895 (and later MRI, CT and ultrasound technology), alongside blood and sample testing, have also improved the diagnostic procedures, allowing doctors to manage illnesses and chronic conditions with a myriad of new treatments that have developed over the past century.
Life expectancies in the world's least developed countries (LDCs) are still rising, especially in Sub-Saharan Africa, but the pace of progress is much slower than it had been in other regions. In recent years, climate change and global geopolitical instabily have increasingly exacerbated the pre-existing regional instabilities that have hindered development for decades. Historically-slow responses to pandemic outbreaks have also been detrimental to the quality of life in many parts of Africa, and the outbreak of the HIV/AIDS pandemic in the 1990s caused life expectancies in some countries to fall by around 15 years in some countries. Nonetheless, coordinated responses, both internationally and on a local level, have seen the threat posed by such endemic diseases fall considerably.
There are additional human-made factors that influence the gender disparity in life expectancy. For example, men's occupations tend to have higher risk of accidental death or the development of debilitating conditions. Death rates through conflict, violence, and suicide are also much higher among men; globally, these rates are mostly on a long-term downward trajectory, although there are significant fluctuations depending on the time and country. As societies grow more wealthy, there is also an uptick in unhealthy lifestyle choices, such as smoking, alcohol and substance abuse, unhealthy diets, sedentary lifestyles, which tend to affect men more than women. A notable example of this is in many former-Soviet countries, where women have a life expectancy roughly 10 years higher than men, and one study suggests that alcohol abuse alone has widened this gap by over two years.
Pre-industrial life expectancy
A global average of roughly 24 years is often given for pre-industrial life expectancy across the world, although this is not an exact science. Life expectancy would have fluctuated regularly due to factors such as food instability, pandemics, and even seasonal weather, therefore a figure of 24 years serves as an average over extended periods. These fluctuations would have happened on a regional basis, and there were also geographic factors that contributed to higher life expectancies in some areas. For example, islands such as Britain or Japan were sometimes recorded as having a higher life expectancy than their continental counterparts, as it was more difficult for disease to spread across natural barriers - this is how Japan avoided the bubonic plague pandemic that swept across Eurasia in the 14th century. However, while these societies may have enjoyed lower death rates, the arrival of disease was often devastating due to lower natural immunity and familiarity. The most obvious example highlighting this was the introduction of Old World diseases to the Americas during the Columbian Exchange, but there are also records of regional pandemics having disproportionately large death tolls in areas such as Iceland or Britain.The figure of 24 years may also paint a misleading picture of age-composition across pre-industrial societies. Infant and child mortality was so high that a quarter of babies didn’t make it to their first birthday, and another quarter didn’t survive until adulthood, but those who survived adolescence could expect to live well into their 50s or 60s. Yet, life expectancy among older groups was still much lower than today, as medical knowledge and technology was not advanced enough to deal with additional factors such as surgeries, infections, chronic and degenerative diseases, among many others.
Why did life expectancy increase?
The gradual increase in life expectancy begins with the onset of the demographic transition, where sharp reductions in infant and child mortality see more people surviving into adulthood. Medical advancements are generally attributed with playing the most important role in this, but other major contributors include improved sanitation and water hygiene, infrastructure, food security, and better education among parents. In terms of vaccines, the development of the smallpox vaccine in 1796 and its eventual eradication in the 1970s is considered by many to be the most important medical development in history, especially given the diseases’ disproportionate impact on children. History has also shown that when the threat posed by one disease is removed, it then allows for resources to be redirected into tackling other medical threats, with diseases such as polio, measles, rubella, and diphtheria now following in smallpox’s footsteps.However, the reduction in child mortality is not the only driver of increased life expectancy, as humanity has also got better at keeping adults alive, and many groundbreaking medical advances have had more impact on the adult population. For example, the discovery of antibiotics in 1928 has greatly reduced the danger of many injuries and surgeries, as has modern anesthesia since the mid-1800s. The development of medical imaging technology since x-ray’s discovery in 1895 (and later MRI, CT and ultrasound technology), alongside blood and sample testing, have also improved the diagnostic procedures, allowing doctors to manage illnesses and chronic conditions with a myriad of new treatments that have developed over the past century.
Regional differences
Countries across the globe have not developed at the same time or pace. In the mid-18th century, the first countries to demographically develop were generally found in Western Europe, North America, and some western Pacific states. These were followed by much of Eastern Europe, Asia, the Middle East, and Latin America, where shared technologies between countries and government policy regarding healthcare (especially vaccination programs) has seen many so-called "developing countries" develop at a much faster pace than Western countries. Today, countries such as Costa Rica, Kuwait, and Thailand have higher life expectancies than the United States, challenging many preconceived notions of the “developed” and “developing” world.Life expectancies in the world's least developed countries (LDCs) are still rising, especially in Sub-Saharan Africa, but the pace of progress is much slower than it had been in other regions. In recent years, climate change and global geopolitical instabily have increasingly exacerbated the pre-existing regional instabilities that have hindered development for decades. Historically-slow responses to pandemic outbreaks have also been detrimental to the quality of life in many parts of Africa, and the outbreak of the HIV/AIDS pandemic in the 1990s caused life expectancies in some countries to fall by around 15 years in some countries. Nonetheless, coordinated responses, both internationally and on a local level, have seen the threat posed by such endemic diseases fall considerably.
Gender differences
Generally speaking, women have always had a higher life expectancy than men. Due to a gender imbalance at birth, there is a ratio of roughly 103-105 male births for every 100 female births, although women eventually start to outnumber men among older age groups. In pre-industrial times, the female population would already overtake the male population in early childhood, as mortality rates were so high among children and young boys tend to be more susceptible to childhood diseases than young girls. However, with time, childhood diseases have become less lethal, modern medicine is more effective at managing chronic conditions, and the world has generally become more safe. In the most demographically developed countries today the female population does not begin to outnumber the male population until societies reach their 50s or 60s, and this even happens among those in their 40s in some Sub-Saharan African countries.There are additional human-made factors that influence the gender disparity in life expectancy. For example, men's occupations tend to have higher risk of accidental death or the development of debilitating conditions. Death rates through conflict, violence, and suicide are also much higher among men; globally, these rates are mostly on a long-term downward trajectory, although there are significant fluctuations depending on the time and country. As societies grow more wealthy, there is also an uptick in unhealthy lifestyle choices, such as smoking, alcohol and substance abuse, unhealthy diets, sedentary lifestyles, which tend to affect men more than women. A notable example of this is in many former-Soviet countries, where women have a life expectancy roughly 10 years higher than men, and one study suggests that alcohol abuse alone has widened this gap by over two years.
