From the Vault: Fingernails, Part 1

How fast do human fingernails and toenails grow? Are they claws and, if not, what are they? In this classic Stuff to Blow Your Mind exploration, Robert and Joe dive into the anatomy, evolution culture and mythology of the “nail as old as time.” (originally published 9/1/2020)

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Episode Transcript

Speaker 1 (00:05):
Hey, welcome to Stuff to Blow Your Mind. This is
Robert Lamb and I'm Joe McCormick, and it's Saturday. Time
to go into the vault for an older episode of
the show. This time we are airing the first part
of our series on finger nails. This originally came out
September one. Yeah, let's dive right in. Welcome to stot

(00:26):
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 the hammer,

(00:47):
though I guess you could hit him with the hammer,
though that would be really bad. 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 or 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 almost always

(01:09):
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, kind of observing like oh,
they're too long, or like, oh, there's some kind of
weird thing here. Perhaps this is idiosyncratic 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

(01:29):
sort of feeling the edges of your nails and you know, see,
making sure everything's lined up there. For my own part,
I tend to find that I noticed them the most
when I am more in the more in the past. Really,
but if I was driving into work and 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,

(01:51):
and 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 herself. I'm also not

(02:11):
a nail biter, 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, so so much like our two
episodes on Tomatoes last week, this is gonna be a
pair of episodes that that are going to get into
some real weirdness. It's and and so I urge you

(02:32):
to stick with us, 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,

(02:52):
they're part of our body, and 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 and claws

(03:14):
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, yeah, I was

(03:35):
thinking about how they're 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

(03:57):
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

(04:20):
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
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

(04:40):
communicate something else entirely. You're gonna look like you're ready
to do some strangling or your 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 vere Joven's Total Recall. Remember the lady who

(05:01):
has nails that she's like touching with the stylus from
her computer and the changing Yeah, very cool. When will
they invent that? Yeah? And 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,

(05:23):
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 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

(05:46):
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 is
that you've got the hard part of the nail. This
plays to fingernails. In tone 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

(06:07):
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,
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

(06:28):
keratin is found in living skin cells as well, and
then the caratonized 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
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

(06:50):
you look at it long enough, it might start to
get a little creepy, yeah, because because there's a 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
and and and we all often know from experience that
it is very sensitive under there. Absolutely, it's sort of

(07:10):
like a window through your skin, but like a frosted
glass window, you know, not exactly 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 the cellular factory.
It turns out new nail plate through cell division over time,

(07:31):
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 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

(07:55):
was looking a little deeper into just the the structural
integrity of the nail. I read an article from back
in two thousand four that was published an Experimental biology
by Firing at All, in which the researchers quote examine
the structure and fracture properties of human fingernails to determine
how they resist bending forces while preventing fractors running longitudinally

(08:17):
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 a you know, but you know, it's it's
a wonderful thing that we tend to see far more
latitudinal cracks than the opposite in other words, cracks tend

(08:37):
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 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

(08:59):
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 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 nails, I believe they were.

(09:22):
They were trimming so that they used in the experiment.
But basically, there are long, narrow cells in the thick
intermediate layer, while tile like cells in 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.

(09:47):
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 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, of
pressure you can exert on that nail. Right, But if

(10:07):
you start trying to go side to side with a
with with the head of a screw, you're gonna find, oh,
it's not really rigid enough to turn the screw. But fortunately,
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

(10:30):
as comfortable and easy as regular like tweezing or pressing
pressure is. Yeah, I mean not to say you can't
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

(10:52):
very interesting contradiction, a sort of psychological contradiction that comes
with the nails which is that they're the parts of
our body that would 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 toenails, is that they generally do

(11:16):
not like this at all. They do not want their
toenails to be messed with, even though it's the hardest
part of their body, and 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

(11:38):
psychology because think about all of the horrifying 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,

(12:02):
if you don't want to hear about any of this,
you know, feel free to skip, like maybe you know,
ten fifty 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

(12:24):
our finger more sensitive, which is something that that 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 by providing
a counter pressure to your fingertip. It gives you special

(12:47):
sensitivity in the skin cells in 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,

(13:08):
I in the past had ingrown tonenails on both of
my my big toes and uh, and had to have
the thing where the the podiatrist 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

(13:29):
other friends who 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

(13:52):
get some some help 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

(14:13):
George Riley Scott, The History of Torture 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 as a
precursor to de nailing. George Riley Scott, by the way,

(14:37):
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, uh,
it was not coming from a super judgmental standpoint, like
a moralizing standpoint. H Well, that's interesting. So we're done
with the nail torture that others inflict on us, I

(14:57):
think at this point. But let's come back to that
other form of sort of nail punishment that we sometimes
do it 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, and

(15:22):
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 biting peaks in early years,

(15:44):
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 bite though, because
the uh, the actual meaning of that is is the
eating of of fingernails, right, I mean it, which is

(16:08):
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 my phegia is the eating of insects and so forth, copperphagia.
We don't need to get into hogegias, the eating of hogs,
of great sandwiches. But even if you're not swallowing the nails,

(16:31):
nicophagia 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, and the author here pointed out that

(16:52):
nail biding can also have dental consequences, So she pointed
to some dental health blogs that I was looking at.
Several of these had dentist citing an estimate from the
Academy of General Dentistry that quote, nail biting can result
in up to four thousand dollars in additional dental bills
over one lifetime. Because there are a number of reasons.

(17:12):
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 kind of aligning your jaw

(17:34):
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, but you're also getting bacteria from

(17:54):
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, it's best to
stay away from it. But that leads to the interesting

(18:16):
question of why we bite our nails in the first place,
and why some people, especially in engage in o nicophagia
like the habitual, repetitive biting of the nails. I was
reading an interesting article about this in Fox by the
science writer Joseph Stromberg, and so he cites that there
were several early theories on nail biting, of course, before

(18:38):
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 grow up to have
this oral fixation, the oral receptive fixation, and which caused

(19:01):
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 between nursing
in early childhood and and so called oral fixations. It

(19:22):
just 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 is a form of o c D of
obsessive compulsive disorder, but not all experts agreed that this

(19:43):
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
Behavior Therapy and Experimental Psychiatry by Sarah Roberts at All

(20:06):
called the Impact of Emotions on Body Focused repetitive behaviors
evidence from a non treatment seeking sample. And this is
a whole class of of behaviors, body focused repetitive behaviors
that can involve nail biting, hair pulling, you know, various
things that were sort of often grooming related, skin picking,

(20:26):
that kind of stuff. And so in this study they
tested people in several different kinds of scenarios that were
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
time they were given to do it. Um. Another one

(20:47):
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 resort to cannibalism? Yeah,

(21:08):
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

(21:30):
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 speech 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

(21:53):
think they're a 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 time fair Oh nice. Uh
well so anyway, so the results of the study were
basically that observed behaviors in reported desire to bite the

(22:16):
nails and engage in these repetitive body focused behaviors. It
singled out two situations especially, which were stress and boredom
and uh In Stromberg's article, he quotes Fred Penzel, who's
a psychologist who helps patients who who deal with nail biting,
and Penzel says of people in these conditions, quote, when

(22:37):
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

(22:59):
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

(23:21):
people say, hey, just wear gloves or put tape over
the ends of your fingers. There's even there are even
companies that make especially tailored, nasty tasting clear nail polished
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

(23:45):
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 to 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

(24:05):
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

(24:29):
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

(24:50):
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 astoni wishing feat of commitment
over time. And this is the story of a doctor
named William Bean. All right, So, Dr William B. Bean
was a physician in a medical historian who lived from

(25:12):
nineteen o 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 addition to 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

(25:33):
that I 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 and peace, at least peace

(25:55):
of mind. They help us maintain our individuality without the
dear 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 are fleeting and falling grains

(26:17):
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. Through the careful and

(26:39):
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 some of this uh, some of

(27:00):
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.

(27:21):
And yeah, so so that 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
the earliest nineteen forty one, and he published his findings
in a series of scientific articles, the first of which

(27:42):
appeared in nineteen fifty three and all 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 to a but uh, like, if if
you clip them eventually or if something comes off of them,

(28:05):
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 uh professor type who has one hand
that has those big, long spiral fingernails up. No, he
didn't do that, uh No, but he did find an
interesting way. Being actually explains in this paper that there

(28:26):
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

(28:46):
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

(29:07):
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

(29:30):
sharp 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

(29:53):
are our 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, it absolutely makes logical sense,

(30:15):
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 worn away. But obviously it happens a lot. Yeah,
I mean, 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

(30:35):
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

(30:58):
in his thumbnail to use as a bench mark. 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,
uh 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

(31:19):
each 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

(31:41):
ratio 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.

(32:03):
So the middle 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. Just 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

(32:23):
a window or something, you need to scratch at it,
and 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 nineteen eighty. He says,
quote a thirty five year observation of the growth of

(32:43):
my nails indicates the slowing of growth with 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 points zero
nine five millimeters a day at the age of sixty seven.

(33:07):
And uh, and pursuing that line of 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 being He writes. The kind of pleasure
and understanding that I get from studying natural history has

(33:28):
long vanished from most contemporary teaching 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 de personalization called
a health center delivers packets of what is termed medical care.

(33:52):
The capacity to look remains, but the 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

(34:13):
long record of the growth of human deciduous tissue. It's
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

(34:36):
measuring the slowing of the growth 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

(34:59):
fingernail grows with just slows and slows, and he's measuring
it in such minute detail that he can see it
happened 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,

(35:22):
So that was But we're gonna take a quick break.
But when we come back, we're going to consider what
more recent researchers 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. Thanks,
thank you, thank you. Alright, we're back al right. So
in the last section we talked about the research of

(35:44):
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 that addresses this by c Claiborne Ray

(36:04):
and uh. The The author here interviews Jeffrey S. Dover,
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 influence
the rate of nail growth. But it's generally accepted that
fingernails grow about three times as fast as toe nails. Robert,

(36:28):
does this square with your experience? I don't know if
it squares with mine. I mean, I don't doubt their findings.
But prior to it 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,

(36:50):
it's probably time to trim my toe nails. Though now
now that I think about it, maybe fingernails do seem
to require trimming a little more frequent only. But I
would don't know. I would have guessed at this particular
rate that it would be three times as fast as toneenails. Yeah.
I don't think I would have naturally come to this
conclusion either, But this seems to be a pretty consistent finding.

(37:11):
Fingernails grow a lot faster, and three times the rate
does seem to be the average of the findings. Um.
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 uh. And then,
speaking to Bruce Robinson, a clinical instructor of dermatology at
Lennox Hill and Mount Sinai Hospitals in Manhattan, fingernail growth

(37:33):
apparently 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

(37:56):
tends to increase 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

(38:17):
that hand for you know, scratching at things, manipulating things
with your fingernails and therefore 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

(38:37):
is there something else at work? Is it more kind
of an adaptation to use of the hand and 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 the Wired article
by Nick Stockton. But the study was by this British
dermatologist named Rodney Dauber who worked at Church Chill Hospital

(39:00):
in Oxford, and I think he sometimes lectured in dermatology
at Oxford 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

(39:21):
playing rugby and so basically this means his finger got jammed.
This usually 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

(39:42):
sounds like that should mean something else, like the tip
of your finger is swelling to baseball size. But with
this injury, Dauber saw an opportunity to test a theory
about why the fingernails grow at different rates, and he's
so so in the spirit of William Bean. Also he
performed this experiment on himself and he published there was
else in Clinical and Experimental Dermatology in nineteen eighty one.

(40:03):
Study was called the Effect of Immobilization on Fingernail Growth.
So Dauber notes that there had been some other theories
to explain the observed difference in nail growth, and some
of these differences were, 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

(40:27):
fastest growing nail, and 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 finger nail, and so

(40:47):
maybe the differential growth is programmed in the genetic level.
Another explanation was possibly people 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

(41:08):
was another theory which is known as terminal trauma, which
I should have checked to see if they ever made
that into like a Michael Doodakov movie or something. But
but the the terminal trauma theory is that the nails
on some fingers grow faster because those fingertips are used
more often. And under this idea, the more fingertip encounters

(41:31):
pressure or damage, the faster it's nail grows. And this
theory would be 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,

(41:54):
your nails grow faster than in people who don't do
these things. Interesting, 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,

(42:14):
and his results supported the terminal trauma theory. In general,
the nails 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

(42:35):
interesting note in general the so if you're if you're
right handed, the left 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,

(42:59):
something that comes to mind on that point and this
would this would have to be something, This would actually
be a kind of topic that I would I would
love to look at it in the future. Is what
what effect does 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

(43:20):
to be heading up or participating in a study of
this sort. And we know from that 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

(43:41):
and sustained pressure on the nails. Um. I don't know,
it's kind of an open question for me. Well, yeah,
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

(44:02):
if if you run around barefoot a lot or often
like kicking at things with your toes, would your toenails
grow faster? Right? Oh? Yeah, that's another good point. Yeah,
like because like I guess, I think of like the
beach person who is going out barefoot at a lot, Like,
on one hand, you're not going to have the end
of your shoe um, pushing against your toe nails or

(44:23):
restraining your feet, but perhaps you're you're more likely to
you know, to scratch around it things, to use your
toenails in a way that is more in keeping with uh,
their their evolved purpose. I guess yeah. I I didn't
find any evidence of whether anybody has studied this question,
but if you are a toenail fingernail researcher out there,

(44:43):
maybe look into this. Does being a barefoot person make
the difference? Yeah, but anyway to summarize it, so, I
think it looks 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
fingertip wear and tear, the nails grow faster. And this
could explain part of the difference in growth made by

(45:07):
handedness and the differences that are observed based on what
we do with our hands, 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

(45:28):
like big cats that have powerful teeth and claws, hard
parts anchored in the bodies for 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.

(45:50):
And what seems to be definitely true is that nails
evolved from organs that were very claw like. Yeah. Yeah,
certainly when we looked at to other primates, uh, we
see uh, we we see true Claus and things more
like like true Claus versus our own fingernails, which are
still useful. Again. Uh, these are very useful to scratch,

(46:11):
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 of course is
is very much the domain of of of of human ingenuity.
You know, Uh. 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

(46:34):
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 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

(46:56):
mouth is language, of course, and the other is fine
motor movements at the fingertips. Right. 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

(47:18):
the thought by many data to to play a role
in the changing shape of our fingers over a human evolution. Um.
So basically, our our primate ancestors had something more like
true clause 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,

(47:41):
we started using tools, and two things impacted the shape
of our fingers and nails. 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

(48:03):
more sense for your finger to narrow more taper towards
the end, Whereas if you don't have a claw at
the end, it makes more sense to have a flatter,
broader fingertip that can probably more easily close around an
object and keep it steady. Yeah, I mean, think of
some of our claude humanoid icons. Think of Edwards s
assor hands or Freddy Krueger or you know, various sort

(48:26):
of humanoid monsters that have long, tapering fingernails. You might
sometimes wonder, well, all right, well, those claws are great
if your trim and hedges there are are 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 um you know, um up the creek
in that regard, Pumpkinhead can't play tennis. Yeah, and then

(48:48):
here's another interesting thing to think about. Um, what about
what what about? Yeah? Okay, obviously, Edwards says, their hands,
Freddy Krueger. You know they have those impressive nails that
they get in the fight. But could they throw a punch?
Could Freddy 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

(49:10):
always have to slash and bite, right, I 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 the tool use seems 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

(49:31):
uh and essentially throw a punch may have played a
role in the form of our hand as well. Oh yeah,
that's an interesting hypothesis though, I mean I wonder um
Iven 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,

(49:53):
and we have some path They may be many years
old at this point, but I remember that was one
of the factors that wasn centered 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 gonna kind

(50:17):
of a delicate balance there. But but this led to
an interesting question that I've often had, uh and and
that is, are sharpened nails useful in a in say
a stand up fight? Would they be an advantage uh
in in a fight? And um, this is one of
these things. It's kind of been like an idle speculation
before I remember. I remember seeing like a music video

(50:41):
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 finger your nails, I think I would honestly be

(51:02):
more worried about about trauma to my fingernails in the
fight then 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 fears of trauma toward them. And if you

(51:24):
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 you

(51:45):
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 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, this

(52:09):
idea of sharpening your nails or having long nails for
you know, to benefit you want to 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

(52:29):
a lot of evidence for the idea that that 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

(52:52):
we would find in other animals. Interesting. Uh so, so
has Danzig never commented on why he's got long finger nails?
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,

(53:13):
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

(53:34):
for me is the way klaus Kinski looks in Werner
Hurtzog's knows Ferrato, 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 had to reacquaint
myself look up a picture that has been a while
since I've I've seen it, though, I guess the original
Nosferato also had some pretty creepy nails, and the Willem

(53:54):
Dafoe version also pretty gastly. Oh Shadow of a Vampire. Yeah,
that's a great movie. Be Actually, I feel like that
that is a sort of forgotten Jim. I need to
revisit it or shadow 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

(54:15):
the same director who had done that really weird art
film Begotten prior to that, which which I don't think
there's really any comparison to be made between the short
film and in the vampire film, but I don't interesting
bit 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.

(54:37):
But Vampires is the perfect lead in to next time,
where we're gonna be talking about corpses and mythology and
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

(54:57):
fingernails in the mean time, 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. 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

(55:19):
might wish to share whether us and we would like
to hear from you. Uh. Likewise, just another reminder that
if you use the Facebook, there 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

(55:39):
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 you want to listen to other 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
asked that you rate, review and subscribe you thanks as

(56:00):
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 shopic
for the future, just to say hello. You can email
us at contact at stuff to Blow your Mind dot com.

(56:22):
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