Fingernails, Part 1

How fast do human fingernails and toenails grow? Are they claws and, if not, what are they? In this Stuff to Blow Your Mind exploration, Robert and Joe dive into the anatomy, evolution culture and mythology of the “nail as old as time.”

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Episode Transcript

Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind production of My
Heart Radio. Hey you welcome to Stuff to Blow your Mind.
My name is Robert Lamb and I'm Joe McCormick, and
today we're going to be embarking on part one of
an exploration of nails. Not nails like you hit with

(00:24):
the hammer, though I guess you could hit him with
the hammer, though that would be really bad. I'm talking
about the kind of nails on the human body. And
I was thinking just the other day about how nails
are sort of the mascot for idleness, for human idleness,
because when humans are idle, what part of the body
is going to get the most attention? I think it's

(00:45):
almost always going to be the nail. Right, You're either
some people bite their nails. If you're not biting your nails,
you're often like looking at your nails and kind of
observing like oh, they're too long, or like, oh, there's
some kind of weird thing here. Perhaps this is idiosyncratics
psychology of mind, but but I think this is pretty common, right, Yeah.
I mean even if you're not even looking at them,
sometimes you just sort of feel them, like you're just

(01:06):
sort of feeling the edges of your nails and you know,
seem making sure everything's lined up there. For my own part,
I tend to find that I noticed him the most
when I am more in the more in the past. Really,
But if I was driving into work, I'd be stuck
in a light or something, and then I would notice
my nails and I would be and that's when I
would notice that I need to trim my nails. And

(01:28):
I would of course be in a position where I
really shouldn't be trimming my nails. Um. And then you know,
the rest of the time, I'm not really noticing them.
That's why the Good Lord made teeth. Well, yeah, we'll
get into that. Uh, that's not particularly my style, but
I know a lot of people do it. My cat
is a big, big fan. I'm also not a nail biter,

(01:50):
but I there are people very close to me who are,
and I have observed the behavior for many years up
close and with a lot of thoughts about it. Yeah,
it's so much like our two episodes on Tomatoes last week.
This is gonna be a pair of episodes that that
that are going to get into some real weirdness. It's
and and so I urge you to stick with us,

(02:10):
even if you think, oh, fingernails, I have those. I
don't want to hear two episodes about it. But really,
I think I think you do. And I think a
great place to start would be just to just touch
on sort of the the obvious, weird aspects of our fingernails.
I was thinking about this today because they're they're obviously living.
They are, you know, they're part of our body, and

(02:31):
yet they're not living in a way right there, like
these things these like little uh you know, almost like
like stones that come out of our our fingers, right, Yeah, Well,
I mean we think of ourselves as non clawed animals.
I think this is a pretty common intuitive grouping of
animals that people make, is like the kind with teeth

(02:51):
and claws and the kind without, And a lot of
them have teeth and claws because you got to it's
a hard world out there. But humans, you know, we've
got tools, and we've got social relationships and we've got
language and all that, so we don't really need claws,
but we kind of do, because we kind of do
have claws, and nails are not super formidable in a
claw sense, but they're kind of claw like. Yeah, I

(03:12):
was thinking about how they're define Our nails are definitely functional,
and we'll get into a lot of those functions as
we progress here. They do play a very real role
in our lives and yet on the same time, at
the same time, they're very ornamental, so that their condition
and their upkeep inevitably communicate something about ourselves to the world.
You know, um, we we can't help but think about

(03:34):
our own nails at times when we're encountering other people,
and like it or not, you're gonna notice other people's nails.
Are they Are they all done up? Are they bright
and colorful? Are they? Are they really making a statement?
Are they? Are they kind of grimy? Are they you know,
they're they spotted with paint? Did they show where? And tear? Like?
These are these are some of the things that are
nails communicate and and it's it's it's like if you're

(03:58):
having a bad hair day or your hair is weird
for whatever reason, you know, you can put on a
cap and that's in many circumstances, and you know you
can kind of get by. But a bad nail day
or bad bad nail days or months or what have you,
that's often kind of difficult to ignore, but on both sides, right,
I mean, you can wear gloves everywhere, but that's gonna
communicate something else entirely. You're gonna look like you're ready

(04:21):
to do some strangling a Bond villain or something, right,
or you know, there actually is another type of nail
that you didn't get to that has always stood out
in my mind ever since I saw this movie when
I was a little kid, Which are the cyborg nails
in Paul Verehoven's Total Recall. Do you remember the lady
who has nails that she's like touching with the stylist
from her computer, And wouldn't they invent that? Yeah? And

(04:50):
for for the time being, we're just left with with paints, right, um.
And we'll get into the use of paints and other
ornamental techniques on our nails as well in these episodes,
because ultimately, yeah, these these nails that we have, um,
are kind of at this intersection of so many different
aspects of the human condition. And if you look close enough,
especially if you go far back into prehistory or or

(05:12):
look around the world at different cultural treatments of nails, Uh,
there's far more strangeness and magic and religious significance than
than people might expect, especially if you're just an American
who just kind of clips them into the trash can.
But maybe we should start with a quick look at
the anatomy of a nail. And now we're not going
to go super deep on this, but the simple version

(05:33):
is that you've got the hard part of the nail.
This plays to fingernails and to nails. The hard part
of the nail is known as the nail plate, and
the nail plate is made out of these compressed layers
of former epidermal skin cells that have been caratonized. Caratonized
as kind of it's your body doing two skin cells
what Medusa does to people who invade her garden of rocks. Uh,

(05:57):
you know, it's it's filling the cells with keratin, which
is this tough, fibrous protective protein that makes up not
only the nails but also the hair and uh, and
keratin is found in living skin cells as well. And
then the keratinized cells in the nail plate make it
not only tough, but relatively flexible and translucent. And the
translucent quality of the nails is I think it's one

(06:19):
of the most interesting things about them. If you look close,
you can kind of see through it to the flesh underneath,
and then to the capillary blood flow under that. If
you look at it long enough, it might start to
get a little creepy. Yeah, because because there's the sense
that the nail is strong. We know the nail is
is strong, and yet the flesh that we see through
that nail window looks very you know, soft and delicate

(06:42):
and and and we all often know from experience that
it is very sensitive under there. Absolutely, it's sort of
like a window through your skin, but like a frosted
glass window, you know, not exactly a transparent, but translucent.
But so where does the nail plate come from. Well,
it comes from the nail matrix, which is found at
the base of the nail, and this is sort of

(07:03):
the cellular factory. It turns out new nail plate through
cell division over time, and as new cells form at
the base of the nail, it pushes the old nail
out from the root, which is why nails grow. Now,
it's interesting to note that there are nails are actually
composed of three layers of that fibrous composite keratin, and

(07:24):
and this is of course a fibrous protein like we
said it's found in hair and feathers and hoofs, claws
and horns. Uh. But I was looking a little deeper
into just the with the structural integrity of the nail,
and I read an article from back in two thousand
four that was published an Experimental Biology by fairn at
All in which the researchers quote examine the structure and

(07:46):
fracture properties of human fingernails to determine how they resist
bending forces while preventing fractors running longitudinally in the nail bed.
So we we've all cracked a nail before. I imagine
it's not a fingernail than a toe nail. That's a
quick thing for me. Yeah, um, and it's you know,

(08:06):
but you know it's it's a wonderful thing that we
tend to see far more latitudinal cracks uh than the opposite.
In other words, cracks tend to be more or less
parallel to the edge of the nail as opposed to
straight up the middle, which would obviously be far more traumatic.
Not to say it doesn't occur, but um, but generally

(08:27):
you're gonna have one that's going across the nail. So
that means that our nails are an isotropic, meaning the
material has a different value when measured in different directions.
And this is much like wood, you know, which is
stronger along the grain, or like meat, you know, the
direction in which you slice a piece of meat makes
a difference in how tender it is. Uh. The same

(08:49):
thing would probably be true of your nails, right, Uh.
And that's exactly what they ended up doing in this experiment,
like tested like cutting on nails, uh, not living the nails.
I believe they were. They were trimmings that they used
in the experiment. But basically there are long, narrow cells
in the thick intermediate layer, while tile like cells in

(09:10):
the thinner dorsal and ventral layers increase bending strength and
prevents cracking from forming. Well, that's very nice, and really
all this lines up with just the way that we
tend to use our nails, uh, scraping, prying, tweezing. If
you've ever tried to use your fingernails as a screwdriver,
you've hit up on some of the design limitations, but
also some of the flexibility of the nail. You'll find

(09:32):
that uh, yeah, if you're just pressing on something, if
you're trying to like dig something out of your own skin,
And you probably shouldn't do that, but if you are,
you'll find that you have a fair amount of you know,
um of pressure you can exert on that nail. Right,
But if you start trying to go side to side
with a with the head of a screw, you're gonna find, Oh,
it's not really rigid enough to turn the screw. But fortunately,

(09:54):
at the same time, um, it's not so brittle that
I just ripped my nail to pieces when I'm trying
and failing to do that. Oh. I've never thought to
put it into words like that, but you're absolutely right,
Like twisting pressure on the nail does not feel as
as comfortable and easy as regular like tweezing or pressing
pressure is. Yeah, I mean not to say you can't

(10:14):
turn a nail. I mean turn a screw a little
bit with your nail. But I think you'll find that
if when it gets to the nitty gritty of trying
to actually put some force into the rotation of the screw,
you're going to realize that you should probably stop what
you're doing and get an actual screwdriver. Now, there's a
very interesting contradiction a sort of psychological contradiction that comes

(10:34):
with the nails, which is that they're the parts of
our body that should be the toughest, you know, the
ones we would put out front as as defensive parts,
the teeth, the nails. There there are defense mechanism. But
one thing you've noticed if you if you ever tried
to trim a dog's toe nails, is that they generally
do not like this at all. They do not want

(10:56):
their toe nails to be messed with, even though it's
the hardest part of their body. You can mess around
with the soft parts of their body. They're usually fine
with it, but you start going in for the nails
and they get all squirmy and say, I want to
clatter around on the floor forever. Uh, And you will
not get a chance to do this. And there's actually
a similar kind of contradiction I think that goes on
in human psychology because think about all of the horrifying

(11:19):
images that people You know, they occur in movies, of course, unfortunately,
sometimes they're practiced in reality, and they all probably just
occur to us naturally. When you imagine something bad happening
to your nails or your teeth, it's like a particular
kind of vulnerability obsession. Yeah, and and I should add,
if you don't want to hear about any of this,

(11:41):
you know, feel free to skip, like maybe you know,
ten fifteen, twenty seconds. But we're not gonna dwell on
this long or in great detail. But but yeah, it
should be noted that fingernail based torture goes back quite
a ways given the delicacy. And certainly there are a
lot of nerves in our fingers and the nail actually
makes our finger more sensitive, which is something that that

(12:04):
I hadn't really thought about before, but this was pointed
out by Evan Writer, assistant professor in the Ronald O.
Pearlman Department of Dermatology, n y U langon health, quoted
in a Mental Floss article by Jordan Rosenfeld from two
thousand eighteen. Yeah, the way I've read it put is
that the by providing a counter pressure to your fingertip,
it gives you special sensitivity in the skin cells in

(12:27):
your fingertip that wouldn't be there otherwise. Yeah, which is
something to keep in mind the next time you have
some sort of issue with your nails where you find
yourself asking that question, why do I have these What
is what good are these nails doing me when they're
causing me so much discomfort right now? UM I know,
for for my own part, I in the past had

(12:48):
ingrown toenails on both of my my big toes and
uh and had to have the thing where the the
the pediatrists goes in and like removes a section of
the toenail and kills the nail bed underneath it, um
to to prevent that kind of thing from happening. And
I kind of get the impression that this is not
all that uncommon because I have other friends who we

(13:08):
we've compared toes and we're like, oh, yeah, you had
the same thing done. Well, I'm sorry you had to
endure that, Robert. But I also do find it quite
amusing that you have you have toe parties with your friends. Well,
you know, I have to say that the procedure is
far preferable to an ingrown toenail. Uh. So if if
you uh, you know, if you're having issues like that,
and you should definitely try and get some some help

(13:30):
with it. That is not yourself toying around and trying
to perform some sort of amateur surgery on yourself in
the bathroom, because that's only going to result in more pain. Um.
Speaking of which, I have to admit that I did
not have the stomach to really dive into this topic
of of nail torture in depth. I know there's a book,
famous book by George Riley Scott, The History of Torture

(13:53):
throughout the Ages, and I skimmed that a little bit
and quickly realized that my eyes were a little bigger
than my stomach on that one. Um. But basically you
have a lot of accounts of de nailing in there,
either by just pulling the nails out or by first
using the insertion of a red hot nail beneath the
fingernail is a precursor to de nailing. George Riley Scott,

(14:14):
by the way, also wrote a history of prostitution in
the early twentieth century that I understand was one of
one of, if not the first histories of prostitution that
was not like, it was not coming from a super
judgmental standpoint, like a moralizing standpoint. Uh. Well, that's interesting.
So we're done with the nail torture that others inflict
on us, I think at this point. But let's come

(14:37):
back to that other form of sort of nail punishment
that we sometimes do it to ourselves nail biting. Oh yeah, So,
as I said before, I am not a habitual nail biter,
but I have observed a bunch of it up close
over the years, and so I don't know, I've I've
sort of like mused on it for a long time.
So habitual nail biting is known clinically as on ecophagia,

(14:59):
and and studies have found somewhere between maybe twenty to
thirty percent of people in total do it, though it
varies a lot by age. UM. So the twenty to
thirty percent figure comes from a study published in twenty
seventeen and the Journal of Dermatological Treatment by Pierre Halte
at All. But according to some sources, nail biding peaks

(15:21):
in early years, especially in teenage years, with some estimates
as high as forty five percent of teenagers doing it regularly,
which sounds very high. But then again, I guess I
don't know what teenagers do. I do have to come
back to um the name of the habitual nail biding though,
because the uh, the actual meaning of that is is

(15:42):
the eating of of fingernails, right, I mean it, which
is not actually what's going on right, at least not
in most cases. I don't know, maybe who knows what
some people swallow, but yeah, phagia, that's you know, that's
used in the terms for the eating of all kinds
of things. Into phagia is the eating of insects and
so forth, copper phage. We don't need to get into
hog eating of hogs, of great sandwiches. But even if

(16:07):
you're not swallowing the nails own, acophagia can have a
lot of negative consequences. For one thing, that your nails
are very dirty. They are sort of a hot spot
for bacteria on your body, and uh, and so I
was reading several articles about this. One thing I was
reading was an article in The Verge by Alessandra Potenza,

(16:27):
and the author here pointed out that nail biding can
also have dental consequences. So she pointed to some dental
health blogs that I was looking at. Several of these
had dentists citing an estimate from the Academy of General
Dentistry that quote, nail biding can result in up to
four thousand dollars in additional dental bills over one lifetime

(16:48):
because there are a number of reasons. But apparently it's
not good for your teeth to be chewing too much
in any case, and it's especially not good to be
always putting chewing pressure down with your front teeth. I mean,
you think about it, that's not normally how you chew. Normally,
you chew kind of like with the pressing of your
back teeth, But when you're biting with your nails, you're

(17:09):
kind of aligning your jaw in a strange way to
bring your front teeth together and turn them into clippers.
But beyond that, there's also just the the exchange of
bacteria from one place to the other and it and
it actually does go both ways. So you're getting bacteria
from under your fingernails and your fingertips into your mouth,

(17:30):
but you're also getting bacteria from your mouth under your fingernails,
which can cause infections there. And apparently it can be
bad both ways. Yeah, so there's really no upside to
doing it. Um, obviously just stopping is easier said than done.
But but but yeah, from from a purely health standpoint, um,

(17:50):
it's best to stay away from it. But that leads
to the interesting question of why we bite our nails
in the first place, and why some people, especially in
engage in oh nicophagia like the the habitual repetitive biting
of the nails. I was reading an interesting article about
this in Fox by the science writer Joseph Stromberg, and

(18:11):
so he cites that there were several early theories on
nail biting, of course, before we had modern psychology. One
of course was Freud, and Freud grouped nail biting as
one of the obsessions that fell under the oral receptive personality.
And in Freudian theory, the idea was that if a
if a child nursed too much during infancy, they would

(18:33):
grow up to have this oral fixation, the oral receptive fixation,
which caused them to always like chew on their nails
and like put objects in their mouth. You know, the
kind of people who are always like putting a stick
in their mouth or something. But again, you know, this
is Freudian is um. There's no real evidence for this,
and as far as I could tell, there's never been
any evidence that's turned up that there's any connection whatsoever

(18:55):
between nursing in early childhood and and so called oral fixations.
Did seems to be another one of those things that
you know, Freud kind of said it, but there's no
reason to believe it's true unless you're one of those
people that has one of those bumper stickers that says
Freud said it, I believe it. That settled it. Now.
More recently, nail biting has been listed in the d
s M as a form of o c D of

(19:16):
obsessive compulsive disorder, but not all experts agreed that this
is the best categorization for it, as not all forms
of nail biting or universally considered really obsessive um. And
so another theory has emerged that nail biting is sort
of a form of emotion regulation. Just one example of
this is a study from published in the Journal of

(19:39):
Behavior Therapy and Experimental Psychiatry by Sarah Roberts at All
called the Impact of Emotions on Body focused Repetitive Behaviors
Evidence from a non treatment seeking sample. And this is
a whole class of behaviors that body focused repetitive behaviors
that can involve nail biting, hair pulling, you know, various

(20:00):
things that were sort of often grooming related, skin picking,
that kind of stuff. And so in this study they
tested people in several different kinds of scenarios that we're
trying to elicit certain emotional reactions. One was a frustration situation,
in which subjects would be given a difficult job to
do that that could not possibly be done in the

(20:21):
time they were given to do it. Um. Another one
was a boredom scenario where people were left in a
room with nothing to do. Another one was an anxiety
scenario where they were asked to watch an extremely terrifying
movie scene. I think it was a plane crash scene
from the movie Alive. I've never seen it. Is that
the one where the soccer players give resort to cannibalism? Yeah,

(20:45):
that's the one based on true occurrences, But but certainly
is notable for having just a very terrifying and at
least at the time, very convincing airplane crash scene. I'm
not sure how it holds up today, but I imagine
it holds up pretty well. And then finally, there was
a relaxation condition where they're watching a video. They're sitting
in a nice comfy chair and they're watching video of

(21:07):
a pleasant beach scene. That's nice too. I like that
movie a lot. What makes you wonder I kind of
want to see the video, Like, how exactly relaxing is
the speech? What if you're looking at the beach and
thinking like, Ooh, I don't know, sharks. Yeah, I guess
you could, um it certainly remind there are these wonderful
videos called moving Art that you can find on I

(21:30):
think they're on Netflix, and they're basically that kind of vibe,
like really soothing ambient music. Um and then these just
beautiful scenes of things like beaches or mountains and sometimes
wildlife depending on what the theme of the episode is.
But it's some great nap timefair Oh nice. Uh well
so anyway, so the results of the study were basically
that observed behaviors in reported desire to bite the nails

(21:54):
and engage in these repetitive body focused behaviors. It singled
out to sit stuations especially which were stress and boredom
and uh. In Stromberg's article, he quotes Fred Penzel, who's
a psychologist who helps patients who deal with nail biting,
and Penzel says of people in these conditions, quote, when

(22:15):
they're under stimulated, the behavior provides stimulation, and when they're
over stimulated, it actually helps them calm down and he
compares it to nicotine actually, with the idea that the
nicotine and cigarettes can sort of be a stimulant when
you are under stimulated, and it can be a relaxant
when you are over stimulated. Uh So, another question is

(22:37):
how do you quit if you if you're a nail
biter and you want to stop. I've read several ideas.
One of course, is just trying to replace nail biting
with an incompatible alternative activity. So in situations where you
might find yourself biting your nails, have something that you're
doing with your hands that you know you can't bite
your nails at the same time, or alternately, I've read

(22:58):
people say, hey, just work of or put tape over
the ends of your fingers. There's even there are even
companies that make especially tailored, nasty tasting, clear nail polish
so that if you put your fingers in your mouth,
that is disgusting. All right, on that note, we're going
to take a quick break, but we'll be right back.
Thank Alright, we're back. So we're talking about nails. And

(23:22):
one question that I find myself thinking about when when
sometimes I'm bored or idle and I start staring at
my own nails is how fast exactly do these suckers grow? Well,
there is an answer to this, and it varies from
not not only from person to person, but throughout a
person's lifetime. But an average figure that's often cited is

(23:43):
that fingernails tend to grow about zero point one millimeters
per day one tenth of a millimeter per day. So
at this rate, if you wanted to grow nails as
long as a six meter saltwater crocodile, it would take
about sixty thousand days or about a hundred and sixty
four years. But unfortunately, even if you could live that long,
your nails would probably not keep growing at such a

(24:06):
dependable rate indefinitely. And one of the great studies in
the history of fingernail research is actually uh something that
contributes to our understanding of this fact. And it's something
that's also in the spirit of Albert Hofman with LSD
or Barry Marshall, the guy who put a Helicobacter pylori
in his in his stomach to prove that it was

(24:27):
the cause of ulcers rather than say stress or acidic
foods uh it. It is a bold act of self experimentation,
and I will say, an astonishing feat of commitment over time.
And this is the story of a doctor named William Bean.
Oh all right, so, Dr William B. Bean was a
physician in a medical historian who lived from nineteen o

(24:50):
nine to nineteen eighty nine, and he taught medicine at
the University of Iowa College of Medicine and the University
of Texas in Galveston. In a into his medical practice
and his teaching and his research, William Bean was a
prolific writer, and I think it's worth saying that he
was also an unusually good writer. An example that I

(25:11):
saw pointed out in a paper on Bean's life was
a passage that I'm about to read, which which he
wrote simply praising the virtues of books for the dedication
of a library. And I just thought this was so lovely. So, Robert,
do you mind if I read this here? Bean wrote,
Books remind us of friendship. They lead us to equanimity

(25:31):
and peace, at least peace of mind. They help us
maintain our individuality without the austere and crushing loneliness of
those who love only themselves. The wisdom we gain from
books leads us to act as though we were building
our ideas for eternity, mindful that the nature of life
and death are so ordered that we and our works

(25:53):
are fleeting and falling grains of sand in the hour
glass of time. If we can avoid the apathy of
those who claim to know that nothing matters, and the
sheer folly of those who know that they personally matter immensely,
we shall have been worthy successors to that silent company
of physicians, our medical forebears, whose spirits watch over us here.

(26:15):
Through the careful and scholarly making and the wise use
of books and libraries, they build our great tradition. By
following them, we must add to it, as physicians, wise
and humble in the care, the comfort, and sometimes in
the cure of our fellows, in their sickness and in
their sorrow. Oh, that is beautiful. And he actually brings

(26:36):
some of this uh, some of this thoughtful writing spirit
to his scientific papers. So this really remarkable self experiment
that William being carried out is revealed by the title
of a paper that he published in nineteen eighty and
the Archives of Internal Medicine called Nail Growth thirty five
years of observation. That is dedication. And yes, so that

(27:00):
is correct, You are understanding the title correctly. There William
Being meticulously tracked the rate of his own nail growth
for thirty five years, beginning sometime in the early nineteen forties,
I think even as earliest nineteen forty one, and he
published his findings in a series of scientific articles, the
first of which appeared in nineteen fifty three and all

(27:21):
the way up until nineteen eighty. I think the one
in nineteen eighty was the last one. So thinking about
this problem, I immediately would have a question, which is,
how exactly do you track how much your nails grow? Right? Like,
you can look at your nail and I don't know,
it looks this long today. But uh like if if
you clip them eventually or if something comes off of them,

(27:42):
how do you know how much it has grown? Yeah?
I know when when when you brought up this study, Like,
the first thing that comes to mind is some is
like a bearded professor type who has one hand that
has those big, long spiral fingernails up. No, he didn't
do that, uh he know, but he did find an
interesting way. Being actually explains in this paper that there

(28:03):
are a number of ways to track the growth of
your nails. Uh and this is his method quote. I
make an indentation with the little file commonly employed to
open small glass vials. On the first day of each month.
I file a transverse groove just at the edge of
the free margin of the cuticle, being careful not to

(28:24):
push it back or interfere with it. Within a week
or two after marking the nail, the end is recorded
when the mark has just reached the free margin of
the nail exactly one point four or five centimeters from
the start. Early in my observations, I measured nail clippings
by linear growth than by weight. With careful calculations, I

(28:44):
found that anywhere from to more than fifty percent of
the nail had been used up by unnoticed attrition. Not
only does the length of the nail wear away, but
the dorsal surface also wears down. If a fingernail is
trimmed with scissors and not filed, sharp angles can be felt.
Since scissors simply takes away bites without filing, these sharp

(29:08):
points disappear in a day or two from unnoticed wear
and tear. Uh And I found this very interesting. So,
even apart from clipping being observes that somewhere between a
quarter and a half of the mass of the nail
just vanishes over time through regular wear and tear. Yeah,
it's it's we we easily take these these tools that

(29:30):
are fingernails for granted, because we use them all the
time to varying degrees to interact with the world around us.
But they are self replenishing, you know, unlike the various
real tools we use on the on the on natural materials. Uh,
those we inevitably have to replace as they wear out. Yeah,

(29:50):
it absolutely makes logical sense, but it's it's just hard
to square that with my experience because I feel like
I never notice my my fingernails just being were in
a way, but obviously it happens a lot. Yeah. I
mean it's like, like you say, if nothing else, you'll
notice that that the sharp edge will go away, Um,
you know, pretty quickly on its own, even if you
don't file them. Isn't that interesting? Yeah? Uh? And I

(30:13):
also want to note Bean's dedication to accuracy and control,
since he notes that at one point to make sure
that the cuticle itself was not advancing or receding unnoticed
of course, because you know, if the cuticle was moving,
that would change how his measurements were happening with the
with the file in the nail plate. Uh. Just to
make sure the cuticle wasn't moving, Being made a tattoo

(30:35):
in his thumbnail to use as a benchmark. What a
little more on his on his method. This is a
quote from an earlier paper by Being, which was reproduced
in a Discover magazine article on him. I was reading
so being wrights quote. When I first began to measure
the rate of nail growth, I scored marks on all
my nails. Within a few months, I found that each

(30:57):
nail had its own pace. This was clearly distinguishable, even
by the rather crude method that I used. Some nails
grew rapidly, some in an intermediate phase, less rapidly, and
some slowly. The differences were small, but regular. There was
consistency in the variation. So if I applied a ratio,

(31:19):
I could tell by measuring one nail what the others
were doing. And this I did on several occasions. In
simple terms, toenails grew more slowly than nails of the hand,
and the nail of the middle finger grows more rapidly
than the nails of either the thumb or the little finger.
Or the other two middle fingers interact. So the middle

(31:41):
finger is the one that he found to uh to
grow the fastest. Yes, and this is a finding that
has been reproduced in other studies that I'll mention in
a minute. It is surprisingly interesting. Yeah, I would have
guessed the index finger just thinking about like the way
that I interact with things with my finger. Now, I
would think, well, that's the one you're most likely. You know,
you see some sort of strange film on a window

(32:01):
or something, you need to scratch at it, You're going
to use your index surely. Uh So that's that's that's interesting. Yeah, yeah,
it is um And we'll get to possible explanations for
this difference in in just a bit here, but I
want to read being summary of his paper from from night.
He says, quote, a thirty five year observation of the
growth of my nails indicates the slowing of growth with

(32:24):
increasing age. The average daily growth of the left thumbnail,
for instance, has varied from zero point one twenty three
millimeters a day during the first part of the study
when I was thirty two years of age, to zero
point zero nine five millimeters a day at the age
of sixty seven and uh, and pursuing that line of

(32:46):
thought a little further, he actually does get strangely thoughtful
and melancholy about it, or maybe not melancholy, at least
there there's a kind of haunting and beautiful passage, or
at least unusually so for a medical journal paper. And
so this is my last quote from and he writes.
The kind of pleasure and understanding that I get from
studying natural history has long vanished from most contemporary teaching

(33:08):
institutions that have become part of intensive care units, which
are supposed to save the residual intellectual machinery of medical students.
The teeming mass of hope and pain, technical virtuosity, and
depersonalization called a health center delivers packets of what is
termed medical care. The capacity to look remains, but the

(33:32):
capacity to see has all but vanished. Teachers and students
forget that the ability to palpate is not the same
as the ability to feel. As a gentle countercurrent, I
set forth here this most recent five year installment of
the observations of the growth of my left thumbnail. It
is a very long record of the growth of human

(33:52):
deciduous tissue. Its duration has little precedent in clinical medicine
or human natural history. Still, the nail provides a slowly
moving keratin chimograph that measures age on the inexorable absissa
of time. So there's something actually strangely profound going on here,
which is by meticulously measuring the slowing of the growth

(34:15):
of his fingernails over time, he's actually watching his body
become less cellularly productive every single year as the circulation
slows down. As that's one probable, at least partial explanation
for it. As the body grows older, it becomes less
efficient at producing new cells. Uh, the fingernail growth just

(34:37):
slows and slows, and he's measuring it in such minute
detail that he can see it happen month by month
as the body says, all right, we are we're going
to slow down on nail production, but we're all in
on ear hair. My god, I would love to read
a William Bean study on his ear hair. I think
it would be so lovely. All right, So that was

(35:00):
nineteen eighty, But we're gonna take a quick break. But
when we come back, we're going to consider what more
recent research has had to say about nails, and then
we'll get into some other nail related topics before we
close out this first episode on on on the subject.
Thank you, thank you. Alright, we're back, all right. So
in the last section we talked about the research of

(35:21):
a doctor named William Bean who very carefully studied the
rate of his own nail growth for thirty five years,
and he published that study in nineteen eighty. But I
was looking for more recent stuff about the rate of
nail growth, and there was a New York Times Q
and A from eleven that addresses this by c Claiborne
Ray and uh. The The author here interviews Jeffrey S. Dover,

(35:46):
an Associate clinical professor of dermatology at the Yale School
of Medicine, who reports the following. So, first of all,
we still don't know all of the factors that influenced
the rate of nail growth, but it's generally accepted that
fingernails grow about three times as fast as to nails. Robert,
does this square with your experience? I don't know if

(36:08):
it squares with mine. I mean, I don't doubt their findings.
But prior to either but but but if you but
but but prior to this, hey, have you had quiz
me on this, I would have guessed that the rate
was more or less the same. I feel like you know,
just from when it is by observing my nail growth.
When it is time to trim my fingernails, it's probably

(36:29):
time to trim my toenails. Though, now now that I
think about it, maybe fingernails do seem to require trimming
a little more frequently. But I would don't know. I
would have guessed at this particular rate that it would
be three times as fast as toenails. Yeah, I don't
think I would have naturally come to this conclusion either,
but this seems to be a pretty consistent finding. Fingernails

(36:49):
grow a lot faster, and three times the rate does
seem to be the average of the findings. Um uh.
They also, of course, they confirm what William being discovered,
which is that nails tend to grow more slowly as
you get older. And uh, let's see. And then speaking
to Bruce Robinson, a clinical instructor of dermatology at Lennox
Hill and Mount Sinai Hospitals in Manhattan, fingernail growth apparently

(37:11):
peaks in your teens and your twenties and then declines afterwards,
and then there's another very strange fact, handedness, as in
left handed or right handed, appears to affect the rate
of fingernail growth. So if you're left handed, the nails
on your left hand will tend to grow a bit faster,
and vice versa. And the rate also tends to increase

(37:35):
in summer and decrease in winter. And it tends to
be a little bit faster in men than in women,
and tends to be a little bit faster in women
during pregnancy. Well, I mean, on the handedness side of that, Uh,
it would certainly be meeting the demand because you'd be
more likely to to use that hand for you know,
scratching at things, manipulating things with your fingernails and therefore

(37:58):
wearing them down. Yeah, but I mean it makes you wonder, like,
what's the mechanism There is there some genetic kind of
coding for handedness that says, okay, I know you know.
Do your genes say okay, I know that you're left handed,
so let's make the nails on the left hand grow faster.
Or is there something else at work? Is it more
kind of an adaptation to use of the hand, And

(38:20):
so as an illustration of the explanation of this question. Uh,
there there was a study that I came across because
I saw a reference to it in a Wired article
by Nick Stockton. But the study was by this British
dermatologist named Rodney Dauber who worked at Churchill Hospital in Oxford,
and I think he sometimes lectured in dermatology at Oxford

(38:41):
University as well. I couldn't actually find if Dauber is
still alive, so I'm not sure, but I hope he is.
But so, around the year nineteen eighty or eighty one,
Dauber suffered what he described as quote a mallet finger
deformity of the left ring finger whilst playing rugby, and
so basically this means his finger got jammed. This usually

(39:03):
happens when something strikes you hard on the fingertip and
it bends the finger by force, and in doing so
damages the tendon that you normally used to straighten your finger.
I've read that this can also be called baseball finger,
but that that I don't know that sounds like that
should mean something else, like the tip of your finger
is swelling to baseball size. But with this injury, Dauber

(39:25):
saw an opportunity to test a theory about why the
fingernails grow at different rates, and he so so in
the spirit of William Bean. Also he performed this experiment
on himself and he published the results in Clinical and
Experimental Dermatology in nineteen eighty one. Study was called the
Effect of Immobilization on Fingernail Growth. So Dauber notes that

(39:46):
there had been some other theories to explain the observed
difference in nail growth, and some of these differences where,
for example, the nails on our longest fingers tend to
grow the fastest. So remember we mentioned earlier beans finding
that the middle finger has the fastest growing nail, and

(40:07):
so maybe this is an evolutionary adaptation. Since the middle
finger is usually a person's longest finger and likely to
be the first one to come into contact with an
object if you just sort of extend your whole hand,
maybe we have a genetic predisposition to have a fast
growing middle fingernail, and so maybe the differential growth is
programmed in the genetic level. Another explanation was possibly people

(40:32):
whose fingers are immobilized due to hemi parisis or neuropathy
tend to show decreased fingernail growth as well, and so
perhaps the lack of nerve supply slows the growth of
the fingernail. But finally, there was another theory which is
known as terminal trauma, which I should have checked to

(40:52):
see if they ever made that into like a uh,
Michael Doodakov movie or something. But but the the terminal
trauma theory is that the nail as on some fingers
grow faster because those fingertips are used more often. And
under this idea, the more fingertip encounters pressure or damage,
the faster it's nail grows. And this theory would be

(41:14):
consistent with with observations by a Legro, Clark, and Buckston
in the nineteen thirties that both nail biters and manual
workers have more rapid nail growth. So yeah, that's a finding.
If you bite your nails or if you tend to
do you know, hard work with your hands, your nails
grow faster than in people who don't do these things. Interesting,

(41:36):
so just supply meeting demand exactly. So Daubert decided to
test this by comparing the growth of the nails on
both of his ring fingers, both while his finger was
splinted to help it heal from the rugby jam and
while it was unsplinted and in normal use, and his
results supported the terminal trauma theory. In general, the nails

(41:56):
on his left hand grew slower than on his right hand,
but the left ring finger, which was in the splint
that nail grew even more slowly while it was splinted
and thus immobilized, and once he could use his finger again,
the nail grew faster. An also interesting note in general
the so if you're if you're right handed, the left

(42:18):
hand nails tend to grow more slowly than than your
right hand. But no matter how your handedness breaks down,
toe nails tend to grow at the same speed on
the left and right. So this might be a result
of handedness being more important for you know, what you
do with your limbs than footedness. Now, something that comes
to mind on that point, and this would this would

(42:40):
have to be something. This would actually be a kind
of topic that I would I would love to look
at in the future, is what what affects shoes have
on this because because of course we so many of
us wear shoes, of great number of us and certainly
I think individuals more likely to be heading up or
participating in study of this sword. And we know from

(43:03):
the shoes change like the shape of our foot. You
know that these are these are not natural um sheaths
that we're putting our our feet into. And I wonder
if if our shoes would be serving to apply more
of a constant and sustained pressure on the nails. Um,
I don't know, it's kind of an open question for me. Well, yeah,

(43:25):
I wonder I wondered about exactly that kind of thing.
So why did the toenails grow slower than the fingernails?
I wonder if that is natural among all people, no
matter what you do with your feet, or if that
is more an artifact of shoe wearing. Like I wonder
if if you run around barefoot a lot or often
like kicking at things with your toes, would your toenails

(43:45):
grow faster? Right? Yeah, that's another good point. Yeah, Like
because like I guess I think of like the beach
person who is going out barefoot in a lot. Like
on one hand, you're not going to have the end
of your shoe um pushing against your toe nails or
restraining your feet, but perhaps you're you're more likely to
you know, to scratch around it things to use your

(44:06):
toenails in a way that is more in keeping with uh,
their their evolved purpose. I guess yeah, I didn't find
any evidence of whether anybody has studied this question, but
if you are a toenail fingernail researcher out there, maybe
look into this. Does being a barefoot person make the difference? Yeah,
but anyway to summarize it, so, I think it looks

(44:28):
like there's pretty good evidence that when fingertips are put
to more work by touching things doing you know, just
generally manipulating objects, putting pressure on the fingertips wear and tear,
the nails grow faster. And this could explain part of
the difference in growth made by handedness and the differences
that are observed based on what we do with our hands,

(44:49):
such as if you're a manual worker. But that brings
us to I guess the last thing I wanted to
talk about before we have to wrap up this first episode, um,
which is coming back to the idea of humans as
a non clawed animal. Of course, you know, so we
we think about animals like big cats that have powerful
teeth and claws, hard parts anchored in the bodies for

(45:12):
tearing the flesh. The flesh of other animals. And in contrast,
humans don't have claws, so we have tools. We have
a claw like hard tool power at our fingertips. But
in a way, nails are still sort of like claws,
even if in diminished form. And what seems to be
definitely true is that nails evolved from organs that were

(45:32):
very claw like. Yeah, yeah, certainly when we looked at
to other primates, we see, uh, we we see true
claws and things more like like true claws versus our
own fingernails, which are still useful. Again, Uh, these are
very useful to scratch, to scrape, and and and I
think a lot of us find this to be the case.
To manipulate very small objects, uh, which you know, which

(45:55):
of course is is very much the domain of of
of of human engineus. You know, even even those of
us who will have we're fortunate enough or or just
through the luck of our lives, are not doing a
lot of like like like intensive labor. You're still gonna
have to pick up a pin off of the floor
at some point, right, You're still gonna have to occasionally
engage in that kind of uh, you know, a fine

(46:18):
manipulation of small things and for that our nails are
are are perfect. Oh yeah, I mean I would say
probably the characteristic motor activities of human beings compared to
other animals. One is what you do with your with
your like throat and your mouth is language, of course,
and the other is fine motor movements with the fingertips. Right.

(46:40):
But of course we do have tools that that stand
in for a lot of these other uses. So we
don't need a great big old uh, you know, velociraptor
type talent or anything, because we have other tools that
can stand in for that, that sort of claw and uh.
And so this is a thought by many data to
to play a role in the changing shape of our

(47:01):
fingers over a human evolution. Um. So basically, our our
primate ancestors had something more like true Claus and it's
and we have the stunted, flattened versions of Clause. And
the reason here maybe because some two point five million
years ago, you know, or or more, we started using tools,
and two things impacted the shape of our fingers and nails.

(47:24):
First of all, curved nails would have increasingly gotten in
the way of tool manipulation. And then secondly, broader fingertips
allowed us to better grip uh stone tools. Oh, I see. Okay,
So if you have more of a claw at your fingertip,
it makes more sense for your finger to narrow more
taper towards the end, Whereas if you don't have a

(47:46):
claw at the end, it makes more sense to have
a flatter, broader finger tip that can probably more easily
close around an object and keep it steady. Yeah. I mean,
think of some of our clawed humanoid icons, uh, the
of Edwards as their hands or Freddy Krueger, or you know,
various sort of humanoid monsters that have long, tapering fingernails.

(48:07):
You might sometimes wonder, well, all right, well, those claws
are great if your trim and hedges there, or or
you know, harassing teenagers in their dreams. But what do
you do when you need to manipulate another tool? Uh,
you're gonna kind of be uh you know, um up
the creek in that regard. Pumpkinhead can't play tennis. Yeah,
and then here's another interesting thing to think about, Um,

(48:28):
what about what what about? Yeah? Okay, obviously Edwards says
their hands, Freddy Krueger, you know they have those impressive nails.
If they get in the fight. But could they throw
a punch? Could Freddie Krueger throw a punch? How about
these various like a lizard man creatures that show up
in all the manner of sci fi and fantasy. Uh,
they just always have to slash and bite, right, I

(48:49):
mean they couldn't because when you have a clause you're
not You're gonna probably gonna have a difficulty forming a fist.
So we know that that tool you seem to have
played a role in the evolution and form of our hand.
And there have also been some interesting studies that look
at how the ability to to to form a fist
uh and essentially throw a punch may have played a

(49:12):
role in the form of our hand as well. Oh yeah,
that's an interesting hypothesis though, I mean I wonder, um,
I can wonder about the idea of of punching as
an adaptation just because it's so often results in the
injury of one's own hand when you do it right. Well,
that is that is something that these studies have looked into,
and we have some path They may be many years

(49:34):
old at this point, but I remember that was one
of the factors that was considered, Like that sweet point
um in the in the formation of the hand where
it can both potentially form a fist and land a
punch while also maintaining its integrity without damaging the thing
that you need for tool manipulation. So it's doing a

(49:54):
kind of a delicate balance there. But but this will
led to an interesting question that I've often had, uh an,
and that is, are sharpened nails useful in a in
say a stand up fight? Would they be an advantage?
Uh in a fight? And um, this is one of
these things It's kind of been like an idle speculation before.

(50:15):
I remember I remember seeing like a music video or
a poster or Glenn Danzig, uh, the rock musician has
um like sharpened fingernails, and and trying to figure out
like what the limitations and or advantages of that would be. Well,
you know, I gotta say, if I were to imagine
going into a fight with with long, sharpened fingernails, I

(50:38):
think I would honestly be more worried about about trauma
to my fingernails in the fight than I would be
excited about my ability to use them as a weapon. Um.
And this comes back to the duality we talked about earlier,
like our hard parts, like teeth and nails for some reason, Uh,
even though they are the hard parts, we have kind
of like special years of trauma toward them. And if

(51:02):
you had long nails and a real scuffle, that just
seems like a real liability. Yeah, and that that seems
to be part of the consensus. I was looking around
it is I couldn't find any real studies on this,
but I was I found a lot of discussion about
this on martial arts boards. Um So, on one level,
people would say, Okay, in a stand up fight, if

(51:23):
you were someone who's after you at being able to
scratch someone with your nails is not a bad deterrent
because you can irritate tissue. You can you know, you
can go for the eyes. And then also something that
worth keeping in mind is that your nails as they
scrape tissue, they collect tissue, which provides a genetic sample
of an attacker potentially. But others also point out, okay, well,

(51:46):
this idea of sharpening your nails or having long nails
for you know, to benefit you in a fight. Ultimately,
these are the these can end up bending backwards rather
than gouge in a you know, a high pressure situation.
And that also it might make forming a fist that
much harder to do. So, ultimately, it doesn't look like
there's a lot of evidence for the idea that that

(52:08):
our nails are are really a um, you know, that
much of a defensive benefit. Though obviously they can be
used to scratch and claw if neat be so they're not.
They're not completely useless in that regard, but it doesn't
seem like there are a lot of ways to really
encourage them back towards a more defensive claw purpose that

(52:30):
we would find in other animals. Interesting. Uh So, so
his Danzig never commented on why he's got long fingernails.
He doesn't say anything about it. I do not know
it's possible that he did, uh, and I'm just I'm
just not aware of it. I can't say that. I've
read a lot of interviews with the man over the years. Uh.

(52:50):
But I imagine that the case there was that he
did it because it looked cool and creepy, you know,
kind of like, uh, something out of a nos Ferato movie. Right.
Do you see so many and so many different types
of vampires and ghouls and creeps that have have long nails,
long tapering nails, and it you know, it looks creepy
and cool. I would say the ultimate example of that

(53:11):
for me is the way klaus Kinski looks in Werner
Hurtzog's knows Ferrat, where he's got long, creepy nails. Oh
it's it's it's spine tingling. Oh yeah, those are some
Those are some wonderfully nasty fingernails. I do. I had
to reacquaint myself look up a picture of that. Has
been a while since I've I've seen it, though, I
guess the the original Nosferatu also had some pretty creepy nails,
and the Willem Dafoe version also pretty gastly. Oh. Shadow

(53:35):
of a Vampire. Yeah, that's a great movie. Actually, I
feel like that that is a sort of forgotten gym.
I need to revisit it or shadows. Did I say
Shadow of of Vampire? Shadow of the Vampire? I can't
remember what the article is, but it's the one with
Willem Dafoe as Max Shrek and it's it's fantastic. Yeah.
I want to say it's the same director who had
done that really weird art film to Gotten prior to that,

(53:58):
which which I don't think there's really any compar are
some going to be made between the short film and
in the vampire film, but I don't interesting. But of
film trivia, nonetheless, I never saw that one. Well, Robert,
I'm sorry. We're here on vampires, and I know we're
out of time, so we gotta wrap up part one.
But Vampires is the perfect lead in to next time,
where we're gonna be talking about corpses and mythology and

(54:22):
magic and religion, all surrounding beliefs about nails. That's right,
so be sure to uh tune back in. I guess
this will be Thursday. We will continue our discussion of
fingernails in the meantime, if you would like to get
in touch with us, so we'd love to hear from you. Obviously,
you all have fingernails, or at least you've had them

(54:44):
at some point. Uh. The same goes for your toe nails.
You have a useful information about this topic, You have experiences,
you have you have injuries, uh, you have fighting experience, etcetera.
All these things that you might wish to share with us,
and we would like to hear from you. Uh. Likewise,
just another reminder that if you use the Facebook, there

(55:04):
is a Facebook group for our show. It is the
Stuff to Bow your Mind discussion module, which you can uh,
you know, it has to be invited to however it works.
I'm not sure that basically we're not active on any
real social media account out there, but there is a
fair amount of activity in that one little place, so
I encourage you to check it out if you wish.
In the meantime, if you want to listen to other

(55:25):
episodes of Stuff to Bowl your Mind, check out some
of these past topics of discussion. You can find us
wherever you get your podcast and wherever that happens to be.
We just ask that you rate, review and subscribe. Huge
thanks as always to our excellent audio producer Seth Nicholas Johnson.
If you would like to get in touch with us
with feedback from this episode or any other to suggest

(55:46):
topic for the future, just to say hello, you can
email us at contact at stuff to Blow your Mind
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(56:06):
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