A Lifetime Ago

Image by brfcs from Pixabay

Having just ticked over a new year, it’s a fitting moment to think about time.  I have often compared modernity to a fireworks show—dazzling, short, then over—and indeed we often celebrate the New Year with a fireworks display.  Perhaps lasting 10 minutes, the display occupies one fifty-thousandth of the year.  This is like the past 50 years of explosive impact relative to the 2.5–3 million years of humans on Earth, or our 10,000 year agricultural period compared to the time since a different explosion: the Cambrian.  Our current ways are indeed as transient as a fireworks show, also marking a sort of culmination of a long era.  But let’s approach temporal perspective from a different angle.

Growing up, I thought of World War II as ancient history: long before my time. But now, I have lived more than twice the span that separated WWII from my birth in 1970. Only 25 years elapsed between the end of WWII and 1970, while we’re presently 54 years away from 1970. 25 years, I now realize, is nothing! When I was born, WWII was still fresh in the minds of many who had lived through it.  Indeed, both my grandfathers fought in WWII, carrying the physical and psychological scars to prove it.  To my grandfathers at the time of my birth, WWII seemed like “only yesterday,” as 1999 seems to me now.

A related trick is to keep track of the date that was as distant from your birth as you are today. In other words, the year in which your anti-self who lives backward in time would find themselves. For instance, I was born at the beginning of 1970 (which also happens to be the start of Unix time), and therefore find myself about 54 years from my birth date. Thus 54 years prior to my birth date is 1916, smack into the middle of the first World War. I can probably expect my backward self to make it past the turn of the century, before the fireworks show of modern life really got underway: before airplanes, for instance.

But the main point of this post is that the past, and all “history” isn’t really that far back. We’ll play a game based on the question: who was the oldest person alive when the oldest person today was born, and likewise back to the more distant past.

It appears that the oldest person alive today is Maria Morera, 116 years old, born in 1907. How old was the oldest person on Earth when Maria was born? We had nearly 2 billion people by 1907, and it seems a very good bet that the planet hosted someone at least 100 years old, if not 110. To make math simple, I’ll assume that said person was born in 1800.

How old was the oldest person in 1800? Given that the population was roughly 1 billion at the time, 100 years old still seems a pretty solid bet.

I may have lost some people already, who are under the impression that lower life expectancy in the past would translate to younger ages for the oldest person alive. But we need to be careful not to confuse average life expectancy with oldest on Earth. Moreover, even when average life expectancy was around 30, once past adolescence life expectancy surged to the neighborhood 60 or more—even for pre-agricultural hunter-gatherer cultures. High rates of infant mortality pulled the average way down.

This BBC article clarifies the situation, documenting known cases of people exceeding 100-years-old during the Roman empire—lead be damned! At this time, median life spans of notables who did not succumb to violence was 72 years, meaning that half lived longer. Old people—even by today’s standards—have always been with us.

What I am doing here is looking at the extreme tail end: the oldest person on the planet—usually unrecorded—is not the mean, median, or mode. Global human population 10,000 years ago was around one-million. What was a one-in-a-million age? An individual tribe of one hundred individuals might be unlikely to host an elder over 70. But gather up 10 tribes and the chances shoot up. Now take 10,000 tribes and you might even get a hundred-year-old fluke—I suspect highly revered and well tended.

What follows is a table of estimated birth years of the sequence of oldest people on Earth. Due to the rather large population involved, and evidence for exceeding 100 years 2,000 years ago, I use 100 years until the year “zero,” 90 years for a while before that, and 80 into the more distant past. This is quite probably conservative: It is possible that Earth has frequently hosted at least one person over 100 years old for the last 10,000 years.

spans ago birth year
1 1907
2 1800
3 1700
4 1600
5 1500
10 1000
15 500
20 0
30 −900
40 −1800
50 −2700
60 −3500
70 −4300
80 −5100
90 −5900
100 −6700
110 −7500

It therefore takes only about 5 individual human lives stretched end-to-end to reach back to European conquest of the Americas. I don’t know the names of these people, but it would only take five names to stack back to these times. Only 20 names reach back to the Roman Empire. Sixty names gets back to the earliest writing. Roughly a hundred names stretches to the dawn of agriculture. That’s a small-to-medium-sized high school class. We are capable of knowing and retaining the names of that many individuals.

The point is that we view the past as immeasurably distant. But it’s not as distant as we think. Compared to the 3 million years humans have been on the planet, 300,000 years of Homo sapiens, and perhaps 150,000 years of anatomically modern Homo sapiens sapiens, this post-agricultural period is very brief, spanning a surprisingly short list of human lifetimes. An earlier post also worked to put this into perspective.

What do we do with this information? Why do I bother pointing it out—besides being a “cute” way to make the past seem less unfathomably far? I think if more people appreciated how new, bizarre, atypical, unsustainable, and whacked this moment is, more people would be appalled at our present path of destruction, no longer misinterpreting it as a laudable expression of human transcendence and supremacy. More people would start looking for the exits. More people would advocate for a completely different way. By putting it in terms of human lifetimes, which we can understand intuitively from personal experience, we can better appreciate how brief this transient behavior is.

Views: 2002