Key Points:
- Some say evolution works against longevity, and technology is why we live beyond 40 years.
- Others point out the importance of grandparents and say living past 40 is natural.
As modern global civilization emerged, the average human lifespan was half what it is today. For this reason, some have pondered the purpose of life after reaching 40. This intriguing question can be explored from various angles, including biological, historical, and societal perspectives. To understand, we must delve into life expectancy data, evolutionary biology, and the role of modern medicine.
No, We Are Not Supposed to Live Long
Historically, it might seem like humans were not meant to live very long. Archaeological and anthropological studies suggest that before the industrial age, the average human life expectancy was between 30 to 40 years, about half the life expectancy of individuals living in today’s developed nations. That is, during the last 200 years of industrialization, life expectancy doubled in under 10 generations.
From an evolutionary standpoint, the purpose of any species, including humans, is to pass on their genes to the next generation. This process is primarily achieved by surviving long enough to reproduce and ensure the survival of offspring. The natural selection processes did not necessarily favor longevity beyond reproductive years. This is the basis for several theories of aging, suggesting that we are not supposed to live long past our prime reproductive years.
However, relatively recent advancements in medicine, public health, wealth and income, nutrition, behavior, and education have contributed to extending human life expectancy. Diseases that once would have killed us in early adulthood can now be prevented or cured, and we can manage chronic conditions much better than ever before. These advancements have pushed the boundaries of human life expectancy significantly.
In the contemporary world, living past 40 is not only common but expected in many parts of the globe. According to the Central Intelligence Agency (CIA), life expectancy in the United States is estimated to be 80.9 years in 2024. In many other developed countries, life expectancies are even higher. This includes Monaco with an estimated life expectancy of 89.8 years, and Singapore with an estimated life expectancy of 86.7 years.
Still, while people in today’s world may be living longer, the incidence of chronic diseases and disability have risen. According to the World Health Organization (WHO), global life expectancy was 73.1 years in 2019 while healthy life expectancy was 63.5 years. This means that the increase in healthspan — years lived in good health — has not kept up with the increase in lifespan. Considering that people are living longer but still suffering from disease and disability, the question of whether we are supposed to live past a certain age remains.
Yes, We Are Supposed to Live Long
As mentioned above, it would seem that evolution has favored reproduction over longevity. However, the “grandmother hypothesis” suggests that older individuals can significantly contribute to the survival of their genes by helping raise grandchildren, thus supporting longer lifespans in humans as an evolutionary advantage.
When it comes to the average human life expectancy being around 40 years for most of human history, some say this average is heavily skewed by high infant mortality rates. If individuals survived to childhood, they often lived much longer, potentially into their 60s and beyond. After accounting for infant mortality rates, even the ancient Greeks are on record with living for nearly 70 years on average.
For these reasons, whether we are supposed to live past 40 might be less about biological constraints and more about what society and medicine can do to extend and improve the quality of life. As research continues to broaden, our understanding and expectations of aging and longevity will continue to evolve. Ultimately, living past 40 is now a part of human reality, supported by both biological capability and technological advancement.
Notably, a recent study suggests that we have essentially reached our life expectancy limit. If this is true, the primary concern of aging biology may be to improve healthspan. Indeed, the latest research has shown that diet, exercise, adequate sleep, and social connections can greatly prolong our healthspan. Additionally, emerging science suggests that certain types of supplements (e.g., NAD+ precursors and senolytics) can also improve our healthspan.
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