I’ve been reading science journals a lot, while I’m waiting for reactions at work. I need something to do, and mostly they are work-related. But I came across an article which delighted me, and I had to share it with you all. There aren’t many places where I can really let my inner book geek hang all out, but this is one of them! 


It used to be that in order to test a book for science, you’d have to destroy a little bit of it. Somewhat obviously, museums and collectors reacted to the thought of this with horror. However, with the advances of technology and ability to get down to the molecular level with testing, it’s now possible to use erdu for determining what skins vellum was made of…


Well, maybe not vellum. It depends on how you define vellum, versus parchment. In general, vellum was higher quality, formed from calfskin, and was believed to have been most sought after from stillborn or newly born calves (3), which modern science has shown isn’t necessarily true. Instead, through studying the proteins, scientists learned that technology of the Middle Ages was better than we assumed it was. They were able to form onion-skin thin vellum from animal skins, leading to a proliferation of ‘pocket bibles’ in the 13th century. We talk about print runs, in this era of automation and mass production, so to put this in perspective: they postulate that 20,000 of these pocket bibles were produced. That’s an amazing amount of work, and animal hide. Scholars have wondered for years how they managed to sustain that level of production, until they were able to apply science to the books. This disproved both the theories about vast herds of cows being depleted through abortion of calves for making books, and other theories about the use of rabbit or squirrel skins (2).


I love that word: erdu. It’s so cool and weird and it means the little bits you have left when you use an eraser on paper. Mostly, the bits are made up of whatever the eraser is made of (they are not India Rubber any longer as they were in the days of Kipling’s schoolboys, which is sad, but manmade polymers like PVC), and whatever was on the sheet of paper the eraser was rubbed across, gently lifting up and encasing in the erdu. That ‘other’ material is what scientists are testing from old books.


It’s not that they are erasing anything from the page, simply using what is called a ‘dry cleaning’ method to remove the built-up crud of centuries, by creating an electrostatic attraction with the PVC eraser that lifts away the molecules. The book the article highlights dates back to the 1300’s and that’s a lot of time for stuff to accumulate. From the erdu, they were able to learn that this one book was made up of the skins of two species of deer (the cover), 8.5 calves, 10.5 sheep, and a half of a goat (1). Which is pretty amazing, but also weird.


It gets weirder. I was vaguely aware that in some religious ceremonies, you kiss the book. Which action, as you can imagine, leaves a residue of bacteria behind. Can you imagine having the kiss it right after some guy with a snotty nose? Ewww… From these pages, scientists are able to isolate species of bacteria they associate with human hosts, and also DNA (1). However, the pages are ones with oaths on them – you swore, and then you kissed the oath to prove how much you meant it. We don’t do things with that sort of gravitas any longer, do we? Of course, we also know those bacteria are teeming around on the page waiting for the next pair of lips to call home.


While they can’t extricate individual DNA from those pages used by many to prove their devotion, they hope to be able to from a book that was owned by only one person. This could help them build a profile of the person, right down to hair and eye color. Other scientists are more interested in sampling worm poop – they want to know what species of beetles bored through the priceless books and left only their droppings behind in neat tunnels (1).


We have come so far, in these last centuries. From parchment, papyrus, vellum… to rag paper, and pulp paper, and now to electrons leaving a fleeting impression on screens. Even if you all are kissing your computer screens (I don’t want to know!) or slightly less gross, sneezing on them, chances are some as-yet-unborn scientist is not going to be swabbing it for your DNA. Much less being able to tell what you were reading.


For fans of my writing, I’m doing a cover reveal with snippet and blurb for my upcoming novella, Snow in Her Eyes. Let me know on my blog if you like the cover! 



1. Biology of the Book
By Ann Gibbons
Science 28 Jul 2017 : 346-349
Scientists develop new ways to read the biological history of ancient manuscripts.
2. Animal origin of 13th-century uterine vellum revealed using noninvasive peptide fingerprinting
By Sarah Fiddyment, et. al
PNAS vol 112 no. 49 08 Dec 2015 : 15066-15071
This study reports the first use, to our knowledge, of triboelectric extraction of protein from parchment.
3. The History and Biology of Parchment
By Robert Fuchs
Karger Gazette no. 67 2004

45 thoughts on “Erdu

  1. It’s great using the modern science techniques to dispel or answer thoughts about the past. One of these days I will probably be researching some more on parchment and stuff Thanks for putting this here to read and explore.

      1. Bookmarked for future reading. I will wait until my WIP’s are whittled down a bit more and I have caught up on most chores. 🙂

      2. It’s not often that both the MGC and the reference material make me drool… 😀

        Bacterial transmission via touch isn’t too much of a problem if the host environment lacks nutrients or contains inhibitors (like the residue of lye or other parchment-making chemicals). Same reason the average floor or toilet is not a source of infection — most bacteria left there quickly desiccates or starves, and only a relative few can survive by encapsulating. Viruses are more likely to survive but there again it’s hit or miss (some live mere moments outside a warm body, others persist for years).

        Even so a film of dead (or rarely, live) microbes would build up. That hard black sheen on some desert rocks is caused by a skin of bacteria adapted to those conditions… occurs to me that in some cases, this built-up coating may have served to preserve the parchment by reducing exposure to the atmosphere.

        1. Yes – I’m not a germaphobe. I ever find the idiot who taught women they needed to hover to tinkle in a public restroom I’ll beat her with my purse… anyway, it was more the concept of following a guy with a snotty nose and a mustache!

          1. My sons are in DeMolay, and the young men do still kiss the Bible to seal their oaths. They solve the problem of kissing the same spot as the last man by turning the page, when they have more than two young men taking the oath at the same time. When there are only two, man on the left kisses the left page, man on the right kisses the right page.

          2. Yes! This thing of hovering above the toilet seat has been irking me (vast understatement) ever since our trip this summer! Sometimes I had to look at every seat in a large restroom to find one that hadn’t been splattered. And I had to examine the seats carefully before allowing mentally handicapped daughter to go in and use the toilet. I would really like to make a big educational push to stop people from this nasty habit.

  2. This is awesome.

    Friday I was talking with a friend and mentioned that I needed an alternative history angle that allowed technology to be 500 or so years in advance of our own and after some rumination on population pressures and China remaining open instead of closing themselves off (I do like the idea of Europe having something the Chinese actually wanted and were willing to trade for but I don’t know what that could be yet), I then decided to look into the printing press more closely and find out why it didn’t catch on and go wide before it did. I ended the stream of consciousness (seriously, if you don’t got one, get a good sounding board) with the thought of maybe the problem was the paper, not the press, as in you’d need substantial amounts of paper available for years (decades) prior to the press because otherwise there’d be no need for mass production on the one end if the other end has got a significant pinch point. Those were the opening thoughts/speculations and I was going to go searching for more information.

    And here is a good place to start.

    That’s just wild.

    Thanks, Cedar.


    1. Books are luxury items, so expensive Vikings targeted them on their raids. Rich people might own a few. Poor churches don’t even have a whole one; they swap pieces around.

      So, you print this fake book-thing on cheap paper instead of real parchment, and it’s not even in proper penmanship, just these blocky disjointed letters that give you a headache to read. And where are all the colorful illuminations and illustrations? It’s just rows of those blocky letters on paper. Might as well paint a piece of wood to look like a steak, because it’s as much a steak as your paper thing is a “book.”

      The point being, we think of books as a handy way to transfer information. Back then, they were more often signals of wealth.

      Think back to 1960s films with their computers as panels of blinkenlights and spinning tape reels. Computers were for governments and major corporations. They did Important Things. Now we get them for “free” with a phone contract, use them to watch cat videos, and throw them away when the non-replaceable batteries get weak.

      That’s the sort of paradigm shift that was needed before anyone saw the point of cheap reproduction of books; it wasn’t so much what books *were*, but what they were *for*.

    2. The Industrial Revolution happened in Britain. The reason had nothing to do with technology. It was because the throne of England was the booby prize of European nobility. The kings and queens of England might have armies and fleets, but they were dirt poor. Centuries before that “Parliament” thing had somehow gotten control of the treasury, and instead of simply owning a country outright, the monarch had whatever he had brought to the throne with him, plus bits of “personal income” here and there; just dribs and drabs that would hardly pay for a good party, much less a monarchic lifestyle.

      One of those “personal income” dribs was customs duties, which was why HM Customs was positively vicious compared to other countries. Britain became a trading empire because it benefited the monarchy directly; every ship that returned to port, a piece of the action came back to the royal purse, not that damned Parliament.

      The British monarchy enthusiastically backed industrial and technological development because it put money in their own personal pockets. Meanwhile, the Kings of France outlawed entire blocks of technology because they found them annoying (self-propelled road vehicles) or to appease protectionist guilds.

      [basic outline from, “The History of the English-Speaking Peoples” by Churchill]

      I’d suggest the governor of a Chinese province far from the Emperor and his bureaucracy, short of cash and with an open mind…

  3. > kiss

    Once a friend reached out to touch something on the screen of my 21″ Mitsubishi Diamond Scan monitor, which cost more than 1,700 Clinton dollars.

    Twenty-three years later, he still resentfully mentions how I swatted his hand away…

    1. But the screens were made of glass; you could wash them with a paper towel and not scratch them.

      1. Not if you wanted to keep the anti-glare coating intact.

        Most high-end monitors had some kind of coating to keep the screens from reflecting overheat lights.

  4. 1. It should be mentioned that the folks at Wheaton, and particularly Michael Drout Wheaton’s Tolkien guy, have been very big into promoting an interdisciplinary study and genetic analysis of parchment and vellum. Their particular thing has been doing analysis of which books’ parchment came from sheep in the same genetic line. This reveals which books come from the same monastery; and if the monastery in question is known, you have a good idea of their production line. (Besides doing it the hard way, by handwriting and art styles.)

    Here’s some info about the sheep DNA project.

    1. Cool! They did mention in the Biology of the Book article that they were able to tell the specific animal by DNA, but the applications of it weren’t discussed. And yes, this approach takes a lot of the guesswork out of figuring some of the book’s origins out.

  5. 2. The only person who was kissing the Gospel book at Mass in medieval times was the celebrant (ie, the priest or bishop, or if a bishop/bishops be present but not celebrating Mass, all the bishops as well as the priest). The front cover of the book was what was kissed, often on a cross-shaped plaque of metal or ivory that protected the leather cover. Other times, the priest kissed the beginning words of the particular Gospel reading. Either way, he said in Latin, “May our sins be blotted out by the words of the Gospel.” This was a gesture by the priest of acceptance and love for the words of the Gospel passage just read (by a deacon or himself), as well as an Isaiah reference. (To the story of his lips being purified by a burning coal and made holy to proclaim God’s words.)

    But in earlier times, in some places, it was a custom for everyone present to kiss the book of the Gospel. Since the Gospels are the words of Christ Himself, obviously one shows them the maximum respect. Only the Eucharist brings His Presence closer.

    To “adore” is to bring “to” (ad-) the “lips” (os, ore — literally mouth, but also referring to or including the lips). This was both an old pagan Roman gesture of respect for parents, gods, patrons, etc., and a Christian gesture understood in light of the story in Isaiah. (Don’t know if it was a Jewish liturgical gesture.) So there have been a lot of lip kisses of objects in the various Rites and Masses, but mostly only by the celebrant. The priest kissing the altar (or rather, kissing the altarcloth on top of the altar, to be technical) before the start and after the end of Mass is probably the most noticeable one.

    The only custom surviving where multiple people kiss the same object is the Veneration of the Cross on Holy Thursday, which is voluntary and provides plenty of surface area for the squeamish, as well as the option of merely touching or looking at the Cross instead.

    1. Fascinating, thank you! In the article they were talking about an oath which was kissed while the swearing process was going on. That one caught my imagination.

    2. So anyway… I know people do worry about that sort of thing, but it’s kinda germaphobe-ish for a Catholic to be bothered by it. This is the religion where the default way to receive Communion is on the tongue, so it’s a bit late for me to be squeamish. Heck, there are still plenty of places where people want to greet priests by kissing their hands*, because priests’ hands are anointed at ordination and made holy to celebrate Mass. Kissing the book strikes me as more of a beautiful custom than an icky one.

      (* I gather this is a Filipino thing, for one.)

    3. Some scholars of Colonial America have speculated that the practice of exchanging the kiss of peace by having congregants kiss a special piece of wood and then pass it to their neighbor (to prevent excessive kissing of the opposite sex, among other things) may have contributed to the demise of Indian converts, Catholic and Protestant. I have no idea if this was actually true, given all the other methods of disease transmission available.

        1. I would have to look it up, but In the Roman/Latin Rite after Trent and before Vatican II, my understanding is that the Pax was only exchanged by the priest and deacon, or similar pairings. I do not think the Mozarabic Rite or the Braga Rite ever got used in the New World.

          Remember, back then the Kiss of Peace was done at Offertory time, and it took about a second. Not a lot of congregation stuff going on.

          1. Okay, I bet they are talking about the Dominican Use, which is the Mass format reserved for Dominican friar priests. They had “pax instruments” that were passed among all the friars, so yes that could be a thing. (In England, they were called “pax bread”, although they were made of wood or metal.)

            When we think of the New World we usually think of Franciscans, but there were a lot of Dominicans there, too. I think they also had a Use, but I do not know much about it because it is not around now. The Dominicans are still doing their thing in places.

            1. This included Protestants, which is one reason why my eyebrows went up the second time I read the book (I, um, kinda skimmed it right before class the first time. And got caught.) It didn’t sound like something the Congregational denominations (Puritans/Separatists/et al) would do.

  6. “We have come so far, in these last centuries. From parchment, papyrus, vellum… to rag paper, and pulp paper, and now to electrons leaving a fleeting impression on screens.”

    On a bit of tangent and going even further back to the Sumerians and their clay tablets, I’ve often thought when studying history that as the ability to read and write became more wide-spread and even languages became more durable (I’ve read that some cuneiform alphabets were invented and used for a single purpose) the medium we use to record the written word becomes more ephemeral. You can still find (and read, if you have the skill set) a 4,000 years or so old “hard copy” of the Epic of Gilgamesh, but the words I am typing right now are a little power failure away from being lost forever (assuming the power went out before I posted them).

    1. There is definitely an argument for the permanence of the tangible – and as an artist, I work in both physical and digital media. One will be gone soon enough, the other has the potential to last for centuries – which is a bit intimidating if you think too hard about it.

      1. It makes for good writing fodder though if you are working on a story dealing with a “Quest for Lost Knowledge” or “Making Old Tech Work Again” – there are definite patterns to lost knowledge. People usually go into great detail about the strange or the complex, but they will often neglect anything that was considered “common knowledge” at the time – like what went into making a vellum manuscript. You can also see this very clearly in an office environment with complex Excel spreadsheets or Access databases. They work great (or maybe just “great”) as long as the person who created them is still there. Once that person leaves there is usually someone still around who might not be able to create the spreadsheet or database from scratch, but he knows how to maintain or fix an existing one. Once the people with that knowledge leave, the people left only know how to “operate” the spreadsheet/database and eventually the whole thing becomes such a mess that someone else creates a new spreadsheet/database and the cycle begins again.

    2. > epic of Gilgamesh

      …and you can summon it through the networked aether, and have the voice of an electronic djinni read it to you.

      In storage, density seems inversely proportional to durability. Words carve in stone, impressed in clay, inked onto leather, inked onto paper, patterns on magnetic media, patterns in capacitive storage…

      1. When I wrote Tanager’s Fledglings, one of the quirks of the main character is that he loves to learn, and find information. Only… there’s so much of it, one of the first things he had to teach himself to do was set up a proper search so he wasn’t drowned in irrelevant data.

  7. Asimov wrote about indexes to indexes to indexes in one of his novels, where the sum of information was so vast that even the metadata exceeded practical management.

    Search engines like Google simplify things by throwing stupid amounts of storage and computing power at the problem, but their algorithms have a lot of bias built in, shaping results to match what they think you’re asking, or what they think other people were asking for. That’s only reasonable; if people didn’t usually get useful results they’d go to some other search engine.

    The search engines are not so good at *not* giving you avalanches of close-bit-no-cigar results no matter how finely you build a search string.

    If I keep boring deep into Google’s search results, no matter what I’m looking for (tool steel heat treating, ballistics, or whatever), at around page 100 it will always start returning rather specialized types of pornography. I suspect that’s based on stored search results from the local Comcast server or its pool of DHCP addresses. Oh, and if I search on “laser drill” (such services are handy when you need small holes made in hard materials) I get dwarves and steam cannon about three pages down. Every. Single. Time.

  8. The problem of impossible to read media is an interesting one. Are there still 9-track tape drives out there? I used them in my youth, but I haven’t seen a tape reel in decades, let alone something that could read it.

    Some things are figure-out-able. If some future archaeologist finds a record, it should be fairly clear how it works – not to say that the first attempt to play it won’t destroy it. However, a CD or DVD? I can imagine being able to figure out the things have data laser etched onto them. (Can you actually see that with a microscope? I’ve never looked.) But the encoding? Especially since a lot of them are DRMed to make the encoding non-obvious. Seems unlikely. A USB drive? Probably impossible unless you have a lot of them to fry attempting to figure out the voltage/amperage.

    1. There are actually companies out there that refurbish and service 9-track tapes. They were fairly standardized, used for decades, and there’s still a *lot* of data stored on 9-tracks, though NASA and the Social Security Administration were supposed to have moved all their stuff to new storage long ago…

      Early-style CDs used pits burned in a metal substrate. They ought to last a very long time. Most modern CDs use lasers to color a dye layer; the official lifetime is 10 years, though I have some over 20 that are still readable. (and I’ve had some that turned into coasters in a week or two; who knows why…)

      You can read an old-style CD with a microscope. As long as it has ASCII text on it, decoding the pits could be solved by classical decipherment methods from the 1800s. Some file formats could be determined. Fonts, GIFs, JPGS… even if they knew what they were, reverse-engineering the algorithms with a pencil and paper would be more trouble than it was worth.

      A thumbdrive in 1900… even if they knew there was data on it, there’s nothing there for voltmeters and ammeters to see. And then the magic smoke would start coming out when they fiddled with the voltage. For that matter, a thumbdrive in 1950 would probably be just as opaque to available methods of reading it.

Comments are closed.

Up ↑

%d bloggers like this: