why we haven’t actually doubled our lifespans

A common refrain says that we live twice as long as our ancestors while it’s our life expectancy that’s increased, not our lifespan. And that difference is extremely important to keep in mind.

old man reading paper

It’s been taken as an almost self-evident truth that over the past century and a half, humans nearly doubled their lifespan thanks to sanitation, vaccination, antibiotics, and technology. But what if that’s not actually true? What if you were told that what changed wasn’t your lifespan but your life expectancy and the two were very, very different things? As detailed in a deep dive by writer and editor Amanda Ruggeri, there’s no evidence that our ancestors saw those in their 30s and 40s as senior citizens. In fact, Romans saw men at those ages as minimally qualified to hold important political offices.

But from where exactly does the myth that we’re living close to double the lives of even our great-great-grandfathers come? As with many problems in public policy and outreach, the problem comes from math, or more precisely, the misunderstanding of statistics. We’re not really living longer than ever. It’s just that more of us than ever are growing past previously dangerous milestones, and are reaching old age thanks to the aforementioned improvements in public hygiene and medicine, as well as being able to stay off the many battlefields during the near constant warfare of the past.

Back in the day, it was dangerous to be a child under ten or a woman in childbirth for a wide variety of reasons dealing with nutrition and unhygienic birthing practices. It was dangerous to live in cities and catch diseases no one knew how to treat. And it was dangerous to get a deep cut infected since there were no antibiotics. So, if you were lucky enough to a) avoid infection, a disease that your immune system can’t beat, survive childbirth, both as a mother and as an infant, avoid direct combat, and be born with good genes, you could technically live into your second century, or at least into your 70s and 80s.

Problem is, a lot of people just weren’t that lucky. When you factor in extremely high child mortality rates, women in their prime dying of childbirth, men at their peak slaughtered in battle, and otherwise healthy middle aged peasants and nobles dropping dead of sepsis and disease, the lucky elders don’t contribute much to average life expectancy. The scientific and engineering revolutions that brought us the modern world spread across the globe and took luck out of the equation. We can now expect to grow old and be right about that in the vast majority of the time in wealthy and even middle-income nations.

And this seemingly semantic note is actually extremely important because it shows that any futurist or Singularitarian claiming that we’ve doubled our lifespan “on the exponential curve of technology” is completely wrong. We’ve done absolutely nothing to change how long we can live, only how long we can reasonably expect to survive and are only now starting to figure out what real life extension looks like and how it could work. Likewise, anyone selling what they claim are life extending treatments, using the rise in life expectancy as evidence of a track record for their claims is either lying or delusional.

On the flip side, alternative medicine practitioners who use documented cases of our ancestors living into what we consider to be old age today as proof that whatever snake oil they’re about to sell you was passed down to them by ancient healers way ahead of modern medicine are just cherry picking woefully incomplete statistics. In reality, the census records we do have before the Middle Ages are spotty and only show us that our ancestors could live to similar ages we do today, not how often that was the case. We only have more or less rigorous, accurate data sets over the past few centuries and they show the potential for a long life with numerous diseases and complications just waiting for their chance to cut it short.

We should absolute celebrate our ability to keep the average person alive longer and staying healthier and more active than earlier generations, and that our ability to do it is constantly improving. But we should also be realistic and understand that we’re just now scratching the surface of the aging process and how to fight it, and only now understanding what sort of data we should be collecting to prevent diseases before they even start. If we want to actually double our lifespan, not just life expectancy, our efforts are only just beginning.

# health // life expectancy / lifespan / longevity


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