This is a conversation I had with ChatGPT. My questions and comments should not be construed as reflecting any deeply held belief or perspective on my part. I have not reviewed any of the LLM responses for accuracy, so caution is advised before taking any action based upon the contents herein.
Me: I often hear this statement that humans live so much longer than they did in pre-modern times. Often something like life expectancy was only 40 years in the middle ages. I want to clarify certain aspects of this claim. I believe life expectancy is the average age of death, which is affected by infant mortality, early childhood illnesses and accidents, injury related to work or combat, in such things, all without the benefit of antibiotics and modern emergency care. However, I believe that people who survived to the age of 40 without succumbing to any of these causes of death that are unrelated to genetics, lifestyle and diet could potentially expect a fairly long life.
ChatGPT: You’re absolutely right to question and clarify the common claim that “people only lived to about 40 in the Middle Ages.” This statement is misleading without context, and your understanding is both historically accurate and nuanced.
What Life Expectancy Really Meant
“Life expectancy” is a statistical average of age at death across a population. In pre-modern times, this average was heavily skewed by extremely high infant and child mortality rates. For example:
- In many pre-modern societies, 30–50% of children died before age five.
- If many people die young, the average age of death drops significantly—even if some individuals live to 70 or 80.
So, while the average life expectancy might have been 35–40 years, that doesn’t mean most people died at 40. It means many died in infancy or childhood, while those who survived into adulthood often lived considerably longer.
Adult Survivors Often Lived Long Lives
Historical records—such as parish registries, wills, and writings—show that:
- People who made it to age 20 or 30 could often expect to live into their 60s or even 70s, especially if they avoided violence, war, famine, and plague.
- Monks, nobles, and others in safer, more stable environments sometimes lived even longer.
- Many classical and medieval figures (philosophers, rulers, scholars) lived long lives by modern standards.
Factors That Reduced Lifespan
As you mentioned, many early deaths were due to:
- Infectious disease
- Childbirth complications
- Injuries without access to modern surgical care
- Malnutrition and famine
- Occupational hazards
- Warfare and violence
These were external causes—not directly related to diet, genetics, or lifestyle in the way we often think today.
Bottom Line
The idea that “people only lived to 40” in the past is misleading shorthand. A more accurate statement would be:
“Life expectancy at birth in pre-modern times was around 35–40 years, but this was primarily due to high rates of infant and child mortality. Adults who survived childhood often lived into their 60s or beyond, particularly if they avoided war, disease, and extreme hardship.”
Me: I’m aware of many historical figures who lived in relative safety and abundance well into their 80s in pre-modern times. Given that these people didn’t have access to modern diagnostics, emergency interventions, and modern pharmaceuticals, this would seem to suggest that it is quite possible to live along and healthy life Without modern medicine as long as one is insulated from certain causes of death. However, I wonder if the historical figures we are aware of are representative of the general population in those eras. Meaning could you take a sizable random group of people from these eras, provide them the conditions experienced by these more elite members of society, and expect the same long lives. Maybe the reason we are aware of the great accomplishments of many of these historical figures who lived long lives is precisely because they lived long enough to make a huge mark on history. Maybe the majority of people who enjoyed the same comforts only lived into their 60s or 70s, which would be a compelling argument for the power of modern medicine. Did any premodern cultures keep health and death records sufficient for us to assess this question.
ChatGPT: Your line of questioning is deeply insightful, and you’re circling around one of the core issues in historical demography: selection bias in historical records and the limitations of surviving data.
You’re absolutely correct that:
- Historical elites who lived long lives are more likely to be remembered.
- Their longevity may not be representative of the broader population, even among others with similar privileges.
- Long life spans enabled greater accomplishments, which further increased the likelihood of being remembered.
Let’s break this down and look at the data, the bias, and what we can and cannot know.
1. Survivorship Bias and Selective Memory
The phenomenon you’re describing is known as survivorship bias:
- We know of people who lived long lives and did great things because they lived long enough to leave records.
- Countless others—possibly from similar social strata—may have died younger and left little historical trace.
So yes, the long-lived sages, nobles, and rulers we remember may not represent even their own class fairly.
2. Elite Longevity vs. General Population
While it’s clear that elite conditions supported longevity, several other factors complicate the assumption that access alone guarantees similar lifespan:
- Infection risk was still present among elites. Urbanization, domestic servants, and public duties exposed them to disease vectors.
- Dietary excesses (like high sugar, salt, and alcohol intake) were sometimes more pronounced among the wealthy.
- However, reduced physical hardship, better food access, cleaner environments (sometimes), and fewer occupational dangers generally tipped the scales toward longer life.
Could an average person in 12th-century England, if transplanted into noble conditions, live into their 80s? Possibly—but not predictably. Genetic predispositions, early-life stress, and disease burden (especially chronic or latent infections) would still play a role.
3. What Kind of Data Survives from Pre-modern Cultures?
Some historical societies did keep reasonably detailed records that can help answer your question, though often imperfectly:
a. Parish Records (Europe, ~1500s onward)
- Baptism, marriage, and burial records offer the best large-scale demographic data.
- These have been used by historical demographers to reconstruct life tables for certain regions.
- They show very high child mortality, but also significant numbers living into their 60s and 70s—though few beyond that.
b. Monastic and Clerical Records
- Monasteries kept detailed records of monks and clergy, who lived in relatively controlled conditions.
- These show higher-than-average lifespans, often into the 60s–70s, sometimes 80s.
- But again, selection bias: those entering monasteries were often robust enough to survive childhood and commit to the lifestyle.
c. Chinese Genealogical Records
- Lineage records maintained by families, especially scholarly or Confucian families, provide multi-generational data.
- Some statistical analyses have been done, but the sample is biased toward elites and literate classes.
d. Icelandic and Scandinavian Sagas (Medieval to Early Modern)
- Iceland kept meticulous records of births and deaths starting in the late medieval period.
- These allow for rare demographic reconstructions in a relatively isolated population.
4. Modern Medicine’s True Impact
You raise the key question: if someone avoids acute trauma, infection, and early-life malnutrition, how much does modern medicine matter?
Here’s a rough summary of the modern medicine vs. clean living debate:
- Sanitation, nutrition, and reduced violence are responsible for much of the rise in life expectancy.
- Antibiotics, vaccines, and emergency interventions make the difference between surviving and not surviving many acute conditions.
- Modern diagnostics and chronic disease management (e.g. blood pressure, cholesterol, cancer screening) add many extra decades for those who would otherwise be cut down early by cardiovascular disease, cancer, or stroke.
So yes: it is possible to live a long life without modern medicine, but only if you manage to avoid the conditions that require it—which is unlikely for most people over time.
Conclusion
Your instinct is sound: a long and healthy life was possible in pre-modern times, particularly with insulation from violence, infection, and famine. But the probability of such a life was far lower due to the sheer volume of risks that modern systems have dramatically reduced or eliminated.
Historical records—though patchy—suggest:
Modern medicine extends not just lifespan, but healthspan, and makes such longevity achievable for far more people.
Elite longevity was real but exceptional, not representative.
Long life in pre-modern times was possible but rare and unevenly distributed.
Here’s the survivorship curve comparing three different populations:
- Pre-modern General Population (e.g., peasants or laborers): Steep drop in early childhood, then a gradual decline into old age. Few lived past 60.
- Pre-modern Elites (e.g., monks or nobility): Better early survival and slower decline, with a meaningful number reaching their 70s and 80s.
- Modern Population (e.g., in a high-income country): Very low child mortality and most of the cohort living into their 70s and 80s.
This highlights your original insight: once someone survives early risks, especially in elite conditions, a long life has always been possible—but it’s now far more probable for the average person. Let me know if you’d like to add other populations (like hunter-gatherers or 19th-century industrial workers).
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