Say what you will about the perils of modern life, at least we live longer than our ancestors. Your life expectancy is quite a bit longer than that of your grandparents, and don’t even get us started about the poor sods who lived centuries ago. How would you like to celebrate your thirtieth birthday, only to contemplate that you will likely die from old age in the next couple of years? You can almost picture a medieval version of the Grim Reaper standing by, the Black Death on one side, famine on the other, just waiting to escort our 12th century forebears into the afterlife.

Before you feel too badly about your great-great-great-etc. grandpa, maybe we should take a closer look at the life expectancy myth. Despite what you may have heard or what you may have been taught, that idea is a little misleading.

While it’s true that early humans faced some truly life-threatening challenges life expectancy stats from back in the day aren’t as doom-and-gloom as they may seem. Grab your actuarial tables and join us as we explore the great life expectancy myth of the Middle Ages.

The Sneaky Role of Infant Mortality in Life Expectancy Stats

If you want the CliffsNotes version, here it is: Those bleak life expectancy figures you’ve heard are averages. As we all learned in middle school math (and promptly forgot), averages can be tricky. You know that thing where you add up all the ages people lived to, divide by the number of people, and voilà, you’ve got the so-called “average life expectancy”? Well, that number is hiding a crucial little detail: infant mortality.

The reason our ancestors seem like they had expiration dates in their 30s is that a whole lot of babies didn’t make it to their first birthday. Diseases like smallpox were the original party crashers. As much as we hate to admit it, even today, newborns in some countries fall victim to diseases like cholera due to lack of clean water. Sad but true, these infant deaths skew the averages big time.

Let’s break it down with a quick math exercise. Picture a group of 12 people—six of whom made it to a respectable age of 70, while the other six tragically passed away at the tender age of 1. Add those ages up (which totals 426 years) and divide by 12. What do you get? An average life expectancy of 35.5 years. Yikes, right? It sounds like they barely got to enjoy their midlife crisis, but here’s the catch: half of them lived long, fruitful lives. It’s just that the other half didn’t make it out of diapers.

The Secret to a Long Life: Don’t Die as a Baby

Here’s the thing: if you could make it through those perilous first few years, your odds of living to a ripe old age were actually pretty solid. Once you dodged the infant-mortality bullet, you could reasonably expect to stick around until 70 or even 80. The problem is, when we use “average life expectancy” as our measure of longevity, we’re lumping together all those unfortunate infant deaths with the grandpas and grandmas who were busy living their best lives. Then again, there’s this study that shows that birthdays are particularly troublesome in terms of health, so take that for what it’s worth.

Let’s take a quick stroll through history, shall we? Over the past 150 years, average life expectancy in the United States has nearly doubled, from around 35-40 years to a sprightly 80. But before you start thinking that today’s humans have magically unlocked the secret to immortality, the real story is simpler: fewer babies are dying. Thanks to modern medicine, sanitation, and the all-important invention of the washing machine (okay, maybe not that last one), more people are getting a fair shot at growing old.

Honestly, at this rate, “40 is the new 20” might be due for an update to “60 is the new 20.” Advances in healthcare are moving fast enough that we might soon need a whole new set of phrases for midlife. One way to do that is to understand micromorts and how certain activities can affect your expected life span. Read more about that in this article.

So, Were Our Ancestors Really Cursed with Short Lives?

It turns out, they weren’t doomed to kick the bucket at 30 after all. Sure, high rates of infant mortality made it seem like most people barely reached their quarter-life crisis, but once they got past those dangerous early years, their odds of sticking around for the long haul were pretty decent. In reality, if you could avoid the baby-killer diseases, there was no reason you couldn’t live a long, full life, enjoying the ancient equivalent of retirement (which, let’s face it, probably involved more foraging than golf).

So, the next time someone tries to tell you that your ancestors all died young, just smile, nod, and remind them that surviving infancy was the real hurdle. Life expectancy may have improved thanks to modern medicine, but the notion that our ancestors were doomed to short, brutish lives? That’s one myth that has long outlived its life expectancy.

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