Bone Song, Read Aloud
two true things about the bone inside your arm — the read-aloud door into Bone Song, Zine No. 1, which is where the argument lives
Put your hand on your arm and squeeze
Not hard. Just a little.
Feel the hard thing under the soft thing? That is a bone. It is yours. It is inside you right now.
This little book is about two true things that are happening in there.
This is the read-aloud door into Bone Song, the first zine on this site. That one owns the argument and this one does not restate it: this is the two facts, made available to a four-year-old.
Large type is for the child. These boxes hold the sources and the limits — including one this subject is usually told without.
A bone is not a dry white stick
The bones you have seen in pictures are dry and white because they are old and empty.
Yours are not like that.
Yours are warm and a bit wet, and they are alive.
They have blood going through them. They grow. If one breaks, it knits itself back together, which a stick cannot do.
This spread exists for a reason that only shows up two pages later: the difference between dry bone and living wet bone is the whole caveat of this zine, and a child who has already been told that bones are wet will not be surprised by it.
Squeeze a bone and it makes electricity
A very small amount. Not enough to feel. Not enough to light anything up.
But real, and you can measure it with a meter.
Push on the bone — the bone answers.
There is a word for materials that do this: piezoelectric. Say it like pee-AY-zo. It comes from an old Greek word that means to squeeze.
Squeeze it, and it sparks a little.
Fukada, E. & Yasuda, I., “On the Piezoelectric Effect of Bone,” Journal of the Physical Society of Japan 12, 1158–1162 (1957). Loading bone produces electrical potentials proportional to the load. The mechanism is shear, not compression: the effect “appears only when the shearing force is applied to the collagen fibres to make them slip past each other,” and its size and sign depend on the angle between the pressure and the bone’s axis. Press straight down that axis and there is nothing to read.
Two names, not one. This site credited Yasuda alone on several pages for a long time; Fukada is the first author and the correction is noted in the colophon.
Two people measured it, a long time ago
Their names were Eiichi Fukada and Iwao Yasuda. They wrote it down in 1957, which was before your grown-up was born, and probably before their grown-up was born.
They pressed on a piece of bone and watched a meter, and the meter moved. Press harder, and it moved further.
And here is the part that most people leave out, and we are not going to.
The bone they pressed on was a dry one.
This is the caveat the popular version of this fact drops, including on this site until now.
Fukada and Yasuda's measurements were made on dried bone. Piezoelectric response falls as the tissue is hydrated — Fukada himself returned to it decades later (Maeda & Fukada, Biopolymers 21, 1982, on the effect of water). In living, wet bone there is a second mechanism: streaming potentials, voltages generated by interstitial fluid being squeezed through tiny channels.
Both are real and they are hard to tell apart. Stress-generated voltages measured in hydrated tissue are not by themselves enough to show the voltage is piezoelectric in origin. Some researchers think fluid flow is the more important signal for the cells; recent work at physiological humidity finds collagen's piezoresponse is still measurable. It is not settled.
So the honest claim is the one the large type makes: squeeze a bone and it makes a little electricity, and this was measured. The claim we are not making is that every step you take is a piezoelectric current telling your bones where to grow.
Some of it, nobody has finished figuring out
In a real live bone, wet and warm, there is something else making a little electricity too: water being squished through very small tunnels inside the bone.
So when a scientist measures a living bone, they get a number — and then they have to work out how much of it came from the squeezing and how much came from the water moving.
They have not finished working that out. People are still doing it right now.
That is not a problem with the science. That is the science.
It is worth letting a child meet an open question early and without alarm. “Nobody has finished working it out” is a normal sentence about a real subject, not a confession.
What is a bone made of?
Mostly two things. Bendy ropes, and hard stuff packed around them.
The hard stuff has calcium in it. Calcium is the same thing that makes a seashell hard, and an eggshell, and a tooth.
Now. Where did the calcium come from?
Not from the shop. Not from the ground, not really.
Bone is a composite: collagen fibres (the bendy ropes) with hydroxyapatite, a calcium phosphate mineral, packed around and within them.
Worth knowing for the previous spreads: the piezoelectric effect in bone is generally attributed to the collagen, not the mineral — the ropes, not the packing.
The calcium was made inside a star
A real star. A big one, very hot in the middle — hot enough to squash small things together and make bigger ones.
That is where calcium comes from. There is nowhere else it can be made.
The star ran out. It blew apart and threw everything it had made out into the dark.
That dust drifted for a very long time. Some of it clumped into a sun. Some clumped into a planet. Some got into the water, and into a plant, and into somebody's dinner.
And some of it is in your arm.
Stellar nucleosynthesis. Calcium, phosphorus, carbon, nitrogen and oxygen — the elements a skeleton is built from — are produced by fusion in stars and dispersed when those stars end. This is settled physics and is the founding fact of this whole site.
Carl Sagan's sentence, verbatim from Cosmos (1980): “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars.” A misquotation of it was corrected on No. 1 in 2026 and the change is in the public changelog.
That star died before the Sun was born
Not before you were born. Before the Sun was born.
There was no Earth yet. No sea. Nobody at all to see it happen.
And the stuff that came out of it is now the hard part of the bone inside your arm, holding you up while you stand there squeezing it.
You are older than you look. Bits of you are much, much older than the ground you are standing on.
The figure is an order, not a scale. The gaps on that line are wildly unequal and no attempt is made to draw them to size; a to-scale version would put the last three marks on top of each other.
The Solar System formed roughly 4.6 billion years ago from material enriched by earlier generations of stars — so “that star” is a convenient singular for what was in fact many.
Both of those are true at the same time
The bone in your arm is made of stuff that was made inside a star.
And when you press on it, it makes a tiny bit of electricity.
You are made of star stuff, and it hums a little when you move.
That is not a poem we made up to be nice to you. People measured both of those things and wrote them down, and anybody can go and check.
We love you down to your star stuff.
“Hums a little” is doing deliberate work: it is smaller than the claim No. 1 makes, and it is the size of claim spread five's caveat will bear.
What this zine does not do is the next step. No. 1 takes these two facts and argues from them — that a bone was silent only for as long as nobody held a meter to it, that a nothing found is a fact about the instrument at least as much as about the thing it was pointed at, and that the belonging in love you down to your star stuff is a promise being made rather than a finding being reported. That argument belongs to that zine and this one hands it back rather than restating it in shorter words. The next spread is the one place this piece points at it.
Not:
Squeeze a bone and it answers. The calcium answering was made inside a star that died before the Sun. Both measured, both checkable, and one of them less settled than we have been saying.
Which of your favourite facts have you never gone back and checked?
What would it cost you to say “nobody has finished working that out” to a child?
When a fact is retold for someone younger, what usually gets dropped — the hedge, or the wonder?
What a read-aloud translation is, and how it is numbered
This is the first of them, so the rule is written here. A translation takes the next number in sequence — the numbers on this site record when a thing was made, and this was made now, so calling it No. 1b would make the number lie. It carries a read-aloud of No. N marker in its card, in the same slot as the existing companion to No. N. And its colophon states that the original owns the argument, which is this paragraph doing that: No. 1 makes the case that a nothing found is not a nothing there. This piece makes the two facts reachable by somebody who cannot yet read them.
Sources
The measurement. Eiichi Fukada & Iwao Yasuda, “On the Piezoelectric Effect of Bone,” Journal of the Physical Society of Japan 12(10), 1158–1162 (1957), doi:10.1143/jpsj.12.1158 — mechanical loading of bone producing electrical potentials proportional to the load — and the effect appearing “only when the shearing force is applied to the collagen fibres to make them slip past each other,” with the sign and amount of polarisation varying “considerably with the direction of pressure.” Read at the full text — see the corrections below for what that changed.
The water problem, which is spread five. Piezoelectric response in bone and collagen falls with hydration — see Maeda & Fukada, “Effect of water on piezoelectric, dielectric, and elastic properties of bone,” Biopolymers 21, 2055–2068 (1982), doi:10.1002/bip.360211010, one of the discoverers returning to his own result; and Marino & Becker, “Piezoelectricity in hydrated frozen bone and tendon,” Nature 253 (1975). In hydrated tissue, streaming potentials from interstitial fluid flow are a second source of stress-generated potential, and observations of stress-generated voltage in hydrated connective tissue are not by themselves sufficient to establish a piezoelectric origin. Recent piezoresponse-force-microscopy work finds collagen's piezoresponse measurable at physiological humidity, and a 2023 study in Journal of Biomechanics reports the two mechanisms coexisting and possibly coupled. The question is live, not closed in either direction, and the zine says so on the child's page as well as this one.
The elements. Stellar nucleosynthesis, settled physics. The Carl Sagan sentence quoted in the spread-eight grown-up box is verbatim from Cosmos (1980).
Three corrections in this zine’s own house
The credit. The effect is Fukada and Yasuda's, in that order. This site credited Yasuda alone for a long time; the correction was made on the Manifesto and the L★S Broadside in August 2026 and was never swept back to No. 1 itself — the founding zine, which still named one of the two. Fixing the instances you noticed is not the same as fixing the fault, and this is that lesson landing on the oldest page here.
The caveat. Before this zine, nothing on this site mentioned dry versus wet bone, or streaming potentials, or that the physiological weight of bone piezoelectricity is contested — while the founding zine and the masthead broadside both state the fact without a hedge. That absence was found by writing this page, and it is recorded in the public changelog rather than quietly patched. What No. 1 says is not false; the effect is real and was measured. It is stated more strongly than the evidence about living bone supports, which is a different thing and still worth fixing.
The mechanism — and this one was ours, not inherited. This zine shipped saying the voltage goes negative under compression, positive under tension, in the spread-four box and again in the sources above. That is the later stress-generated-potential literature. Fukada and Yasuda report the effect appearing only when collagen fibres are sheared past each other, with the sign and size depending on the angle of the pressure. We had cited the 1957 paper for a sentence it does not contain, because we had it at second hand and said so. Ryan put the paper itself in front of us on 7 September 2026. Two lessons worth keeping: “confirmed through the review literature” is not a small discount on reading the thing — and a 2021 review in Bioelectricity states the mechanism correctly on one page and repeats the compression gloss four pages earlier, which is how a wrong sentence stays alive in a literature that also contains the right one. Corrected here and on No. 1 the same day, and in the public changelog.
What this deliberately does not re-argue
No. 1 owns the argument. The reframe — that a null result is a fact about the instrument as much as about whatever it was pointed at, and that the belonging is a promise being made rather than a finding being reported — is made there, at length, and is not compressed here. A translation that re-made the argument in shorter words would be two pieces claiming the same thing in two voices, which is the failure mode this form has to avoid.
A rhyme, not a proof. We are not claiming that a voltage in a bone says anything about a person. We are handing a child two measured facts about their own arm, one of which is less settled than it is usually told, and letting them keep both.