Old age isn’t a modern phenomenon – many people lived long enough to grow old in the olden days, too

Every year, I ask students in the course I teach on the 14th-century Black Death to imagine that they are farmers, nuns, or nobles from the Middle Ages. What would their lives have been like in the face of this terrifying disease that killed millions of people in just a few years?

Aside from how they envision what it would be like to face the plague, these students often think that in medieval times they would already be considered middle-aged or elderly at the age of 20. Rather than being in the prime of life, they thought they would soon be decrepit and dead.

They reflect a widespread misperception that long lifespan in humans is very recent and that no one in the past lived much beyond their 30s.

But that’s simply not true. I’m a bioarchaeologist, which means I study human skeletons found at archaeological sites to understand what life was like in the past. I am particularly interested in demographics – mortality (deaths), fertility (births) and migration – and how they were linked to health problems and diseases such as the Black Death hundreds or thousands of years ago. There is physical evidence that many people in the past lived long lives – just as long as some people today.

Bones record the length of a life

One of the first steps in demographic research in the past was to estimate people’s ages at the time of their death. To do this, bioarchaeologists use information about how your bones and teeth change as you age.

For example, I look for changes in the pelvic joints that are common in old age. Observations of these joints in people whose ages we now know allow us to estimate the ages of people from archaeological sites with similar joints.

Another way to estimate age is to use a microscope to count the annual additions of a mineralized tissue called cementum to the teeth. It’s like counting the rings of a tree to see how many years it has lived. Using approaches like these, many studies have documented the existence of people who lived long in the past.

For example, by examining skeletal remains, anthropologist Meggan Bullock and her colleagues found that in the town of Cholula, Mexico, between 900 and 1531, most people who reached adulthood lived past the age of 50.

And of course, there are many examples from the historical record of people who lived very long in the past. For example, the 6th century Roman Emperor Justinian I is said to have died at the age of 83.

Analysis of the dental development of an ancient anatomically modern Homo sapiens An individual from Morocco suggests that our species has enjoyed a long lifespan for at least 160,000 years.

Clearing up a mathematical misunderstanding

Given the physical and historical evidence that many people lived long into the past, why does the misperception that everyone was dead before the age of 30 or 40 persist? This comes from confusion about the difference between individual lifespan and life expectancy.

Life expectancy is the average number of years left to live for people of a given age. For example, life expectancy at birth (age 0) is the average lifespan of newborns. Life expectancy at age 25 is the average lifespan of a person given that they have survived to be 25 years old.

In medieval England, life expectancy at birth for boys born into land-owning families was only 31.3 years. However, the life expectancy at age 25 for landowners in medieval England was 25.7 years. This means that people of that era who celebrated their 25th birthday could expect to live to be 50.7 years old, on average, or 25.7 years longer. Although 50 doesn’t seem old by today’s standards, remember that this is an average and many people would have lived much longer, into their 70s, 80s and beyond.

Life expectancy is a population-wide statistic that reflects the conditions and experiences of a wide variety of people with very different health problems and behaviors, some dying very young, others living to be over 100, and many whose life expectancy falls somewhere in between. Life expectancy is not a promise (or threat!) about how long a single person will live.

What some people don’t realize is that low life expectancy at birth in any population generally reflects very high infant mortality rates. It is a measure of deaths during the first year of life. Because life expectancy reflects population averages, high numbers of deaths at very young ages will skew calculations of life expectancy at birth toward younger ages. But in general, many people in these populations who are past the vulnerable years of infant and toddlerhood can expect to live relatively long lives.

Advances in modern sanitation – which reduces the spread of diarrheal diseases that kill many infants – and vaccination can significantly increase life expectancy.

Consider the effect of infant mortality on overall age groups in two contemporary populations with radically different life expectancies at birth.

In Afghanistan, life expectancy at birth is low, just over 53 years, and infant mortality is high, with almost 105 deaths per 1,000 children born.

In Singapore, life expectancy at birth is much higher, exceeding 86 years, and infant mortality is very low: fewer than two children die per 1,000 births. In both countries, people survive to a very old age. But in Afghanistan, as more people die at very young ages, proportionately fewer people survive to old age.

Living a long time has been possible for a long time

It is wrong to view longevity as a remarkable and unique characteristic of the “modern” era.

Knowing that people often lived a long time in the past can help you feel more connected to the past. For example, you can imagine multigenerational households and gatherings, with grandparents in Neolithic China or medieval England bouncing their grandchildren on their laps and telling them stories about their own childhoods decades before. You may have more in common with people who lived a long time ago than you thought.

This article is republished from The Conversation, an independent, nonprofit news organization that brings you trusted facts and analysis to help you make sense of our complex world. It was written by: Sharon DeWitte, University of South Carolina

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Sharon DeWitte receives funding from the National Science Foundation.