Life Expectations

A while back, I came across a fascinating paper from 2007 by Gurven and Kaplan on longevity among hunter-gatherers that helped me understand aspects of what life was (and is) like outside of modernity. My interest is both a matter of pure curiosity, and to gain perspective on how desperate life feels—or doesn’t—to members of pre-agricultural (ecological) cultures.

I wrote last year about the perceived perils of early human life in Desperate Odds, in the context that to us members of modernity, having never been weened from the teat of agricultural output, it seems like life without agriculture (and supermarkets) would be a virtual death sentence. Add to this a perceived vulnerability to predation from lions and tigers and bears (oh my!), and the mental image that emerges—as depicted by Daniel Quinn in Ishmael—is of a stressed and starving hunter following the tracks of elusive prey as twilight darkens, while a predator is close on his trail, audibly breathing. It feels like a knife edge of survival: everything has to go just right, but teeters on all going horribly wrong.

The core argument from the Desperate Odds post was that surviving to reproductive age was obviously common, or our species would wink out. This simple fact makes daily survival a near-guarantee—enough so that fear of death is not top-of-mind most of the time, allowing most brain cycles to go toward less-troubled, routine activities.

It was either in preparing that post or in connection with A Lifetime Ago that I ran across the aforementioned paper. In this post, I dig in to see what insights can be gained from survival models for various human cultures.

The Attention-Grabber

Let’s start with the plot that caught my eye and drew me in, which is Figure 3 in the paper.

Figure 3 from motivating paper.

Let’s see if it draws you in as well.

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Your Order, Please?

This may come as a surprise, but people are capable of holding unsupported notions…unexamined beliefs and expectations. A common default assumption—often quite reasonable—is that conditions will continue in a fashion that is recognizably similar to the way they have been during one’s lifetime. Suggestions to the contrary tend to be met with suspicion—or even hostility in the case that the suggested outcome is less than rosy.

What if we presented possible options for future human developments—let’s say human population as a solid example—and pretend it’s a menu from which we get to choose. What outcome would most people see as the desired goal? What would make them happy, or satisfied? Which population curve below do you think most would select?

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Evidence, Please?

I spend a fair bit of time asking myself the question: Am I crazy?

I mean, without really wanting to do so, I seem to have landed on a fringe view within our culture, which is not a comfortable place for me in a social sense. I don’t love it. The easiest—seemingly most likely—explanation for the glaring mismatch is that I’m the one off kilter.

My statement: Modernity (even if defining starting 10,000 years ago) is a short-lived phase that will self-terminate—likely starting this century.

Common response: That’s crazy. Just look around you! We’ve created a new normal. Humans have transcended the bounds of nature—no longer mere animals. Ingenuity has unlimited potential, and we’re really on our way now. This changes everything, and we will never lose our technological mastery, now that we have found it. Modernity is our destiny—and kind-of the whole point of it all.  It’s what makes us truly human.

But let’s look at evidence: like evidence that modernity is a new normal that can go on at least as long as our species is around (relevant timescales are 106±1 years, or a million years plus-or-minus an order of magnitude).

What’s that? Zero evidence? Of course we can’t know. The future is not kind enough to present evidence to the present. Hmmm—maybe that’s because we’re so mean to the future, frantically robbing its lives of Earth’s bounty and biodiversity.

The basic observation that we can receive no evidence from the future cuts both ways, of course. I have no future evidence that modernity will begin shutting down within a century.

However, we are not completely in the dark, here. We know some things (see my previous post on things about which I can be relatively certain).  As obvious illustrations, we can be super-confident that day will follow night in a consistent cycle throughout our lives, that we will each die someday, and that the sun will render Earth uninhabitable on its way to spending its fuel.  In a similar fashion, we can lay claim to a host of other near-certainties even without evidence from the future.

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