There was a short little blurb in the January 15 New York Times magazine about barefooting.
It contained a quote I thought I’d write about.
First, here’s the blurb:
What caught my attention was James Tierney’s comment that his soles
are the same as rhino horns.
He is right on (mostly).
Keratin is the substance that gives horns and hair its toughness. It is also found in nails (and claws), and even hooves, beaks, and feathers.
There are actually quite a few varieties of keratin, a lot of which variance depends on the amount of the amino acid cysteine in it. The cysteine provides crosslinking that provides strength. Normal skin is about 3% cysteine. Hair (and horn) runs about 10-15%.
The skin reacts to pressure by increasing its keratin content (called either cornification or keratinization). When that pressure is localized (like inside of a shoe), that results in a corn. On the bottom of the foot, though, you simply get highly functional callus. This callus formation is innate and provides the sort of protection that Barefoot James is talking about. Obviously, his years of going barefoot have upped the cysteine content of his soles to match (or come close to) that of rhino horns. (And so have most regular barefooters.) I imagine he has some pretty good thickness, too.
Not unsurprisingly, those who wear shoes all the time have pretty low-keratin soles. It’s no wonder it hurts them to walk barefoot (but that’s easily curable!). I’ve never understood the desire of many to have baby-soft soles. To me, that’s like being proud of having anemic arm muscles and touting that you can barely pick up a loaf of bread without straining yourself. Why not develop the body’s capabilities to at least some semblance of useability?
Since I lost the thick skin on the balls of my foot a while back, it has grown back to very near its original thickness. But the newer skin just doesn’t seem to have the strength of the original. Is it growing in with upped keratin?
You can usually tell the keratin content of your skin just by tapping on it with a metal probe of some sort. I have found that a set of dental picks works pretty well.
So, I’ve made a few recordings of tapping on a few different locations. Here is what it sound like if you tap on a toenail, something with an obviously high keratin content.
For low-keratin content skin, I next tapped on the skin under my arch, which touches the ground only rarely, and without much pressure. While this skin is slightly thicker due to its contact with the occasional twig, it is not particularly keratinized.
On my foot, my heel has both the thickest skin and the skin most like a rhino horn.
As you can hear, it’s not much different than a toenail.
Well, what about the ball of the foot. Here’s the tapping on part of the ball that still has original skin.
That’s a bit lighter, but then the skin there is thinner than the skin on my heel. (I think this also makes it obvious that when I hike I pretty much always land on my heel, not my ball.)
OK, and now for the big test. What about the new skin?
It’s a bit weaker than the original ball skin, but not by much. That tells me that the new skin is growing in with a pretty high keratin content, and it is providing me with quite a bit of protection.
That’s good to know, and it is good to have a simple test to find out.
If you are a barefooter, you might experiment with tapping a few different
places on your feet to see just what sort of development you have.