“Wow Simon, this is such an enticing title for a blog post!”

“I know, right?!”

Okay chill out. This is indeed mildly interesting, at least to me, because the thought never occurred to actually measure this. That is, until some time following the events of March 17, 2024:

A slipup washing knives, totally unrelated to this being St. Patrick’s day, resulted in 3 stitches.

Here’s a better pic, 4 days later:

The wound, being a clean incision brought to me by alcohol-impairment and fine German steel, closed within 2 weeks. But as my fingernail grew out, I noticed that it had been damaged behind the cuticle. What started as a divet turned into a flaking nail as the damage neared the fingertip.

Eventually though, the damage grew out and was clipped away. And unlike my toe which slid under the bathroom door while exiting the shower some 30 years ago, the growth cells were not permanently rendered incapable of uniform nail growth. Huzzah! At long last, the injury is fully healed.

So how long did this injury take to completely heal? 181 days! Essentially two full seasons. So back to the original line of thought: what is my nails’ growth rate, and naturally – is that normal? Squander not an opportunity, for I have definitive empirical measurements based on when that crack grew out.

It would appear that, based on photos of the original injury’s location, that between March 17 and September 14, 15 millimeters’ worth of nail grew out. So if we apply some basic math, that’s…

~2.5mm per month, or…

~0.08mm per day.

Which seems like a long damn time to be catching that cracked nail on things. But is that normal?

According to healthonline.com (seems like a legit website), the average nail grows 3.47mm per month, or “roughly a tenth of a millimeter per day”. My math works out to 0.12mm per day, so they’re using fuzzy math, but whatever. Dear God! My nails are growing at 2/3 the average rate for a healthy human! Do I need more alpha-keratin in my diet?

Okay, so digging deeper reveals that’s a rough estimate and nail growth peaks at age 10. I’m 40, so not exactly in my prime anymore, granted. So that means, if my nail growth indeed peaked at age 10, then for each decade since, my nail growth has decreased by 22.2%, if we’re assuming a linear function, which I can only do with two data points. 66.7/3=22.2.

Now the important question: can I use nail regeneration rate as a benchmark for all my cellular regeneration? And if so, can I use that to predict the point at which I’ll no longer be able to adequately heal – i.e. *die*?

Let’s try. So for X, when X = current percent rate of nail growth (66.7%)…

And when Y = # of decades passed since X, then…

My predicted rate of cellular regeneration, C, = 100-((X/3)*(1+Y))

Then we see where C falls to zero. Then I can simply narrow it down by dividing (X/3) by 10 to determine degeneration rate per year.

**My conclusion: I will die sometime just before my 75th birthday!**

Not very encouraging. I think I need more data points. Give me another 10 years and I’ll complete another measurement. I hope the prediction is a little more encouraging, otherwise I’ll be looking at early retirement!

–Simon

P.S., This counts as Quantitative Philosophy!