Published on August 14, 2025 12:15 AM GMT
Knowing how evolution works gives you an enormously powerful tool to understand the living world around you and how it came to be that way. (Though it's notoriously hard to use this tool correctly, to the point that I think people mostly shouldn't try it use it when making substantial decisions.) The simple heuristic is "other people died because they didn't have this feature". A slightly less simple heuristic is "other people didn't have as many offspring because they didn't have this feature".
So sometimes I wonder about whether this thing or that is due to evolution. When I walk into a low-hanging branch, I'll flinch away before even consciously registering it, and afterwards feel some gratefulness that my body contains such high-performing reflexes. Eyes, it turns out, are extremely important; the inset socket, lids, lashes, brows, and blink reflexes are all hard-earned hard-coded features. On the other side, I'll experience something unpleasant, and then be like "why is this still a thing??" Why didn't evolution remove this? Pretty often, it's clear that the unpleasantness just doesn't correlate with actually dying. Case in point; hangnails. And when some feature does actually kill people, it often causes equally many people to live, so removing it is not better on balance. And very often, there is simply no "small" mutation available to the genome that would incrementally reduce it.
And for a huge range of my experiences, natural selection has had approximately zero time to work with it. We are submerged in modernity. The species of Homo sapiens is generally considered to be about 300,000 years old. Looking around me, it can take a minute to think of something that was here even 200 years ago. At some point I started making a mental timeline, to help orient myself when I read about prehistory. All dates highly approximate, kya = kiloyears ago.
- 5kya: Writing emerged. Humans were certainly scratching symbolic references for a while before that, but this basically just happened.12kya: Agriculture.15kya: Monumental architecture. A "city", where most people now live, is an insane super-stimulus version of these first settlements.50kya: Humans migrate into Europe.50kya: Cave paintings. We were almost certainly doing art long before this, on more perishable materials.
These may have had some influence on our genome, especially if the selection pressure was strong, but even 50kya is only 1/6th of our temporal range.
For many other milestones, like the first clothing, music, or use of fire, it is very difficult to have enough evidence to establish an earliest date, even within a factor of 2. But stone tools, the very implements that gave the stone age its name, have a rich archaeological record. It stretches back at least three million years. That's right; stone tools are ten times older than the existence of anatomically modern humans.
And this isn't one of those cases where there is a single oldest claimed instance which is far older than everything else. Archeologists have traced the development of stone tool tech throughout the millions, giving nicknames to the phases of techniques that ancient hominids used.
It's easy to forget how large a ratio can be. Ten apples feels like a normal quantity of apples. But a 1-hour dentist appointment is a lot different than a 10-hour dentist appointment. Not to put too fine a point on it (pun intended), here's the difference between the span of Homo sapiens existence, compared to how long stone tools have been in use:
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Many words have been written about the rejuvenating effect of a walk through nature, the now-rare sight of the milky way, or the way in which our modern life keeps us separated from the complexities of the ecosystems around us. But no one ever talks about how we don't knap flint like we used to.
Of course, the species immediately preceding sapiens was pretty similar to us. So any differences that stone tool use could have made have to be compared with the magnitude of those changes. But Homo habilis would be immediately recognized as different on sight. Even their bipedal gait was still adapting.
And it's not as though every person in the tribe would have been a lithosmith. There was presumably some specialization. But still. Three. MILLION. Years. All that duration of selection can't just be dust in the wind. Around here we pride ourselves on taking ideas seriously, especially when numbers are involved.
Are stone tools the reason I have fingernails instead of claws? (Doesn't seem like it; chimpanzees' fingernails look the same to me.) Was my blink reflex improved by being assailed with chipped projectiles? Do we have seasonal allergies because our mucus membrane was expecting to be coated in a protective layer of chert dust?
Anyway, I think this is starting to read like satire, but I am genuinely curious;
- Are their things about my body that are that way because of stone tool making?Am I missing out on any kind of "nutrient" by not doing it?
Discuss
