Thursday, April 17, 2008

Scribal Error and DNA Mutation

I bet no one thought those two topics would be discussed in the place at the same time, ever. Certainly never occurred to me. But Jonathan Jarret at A Corner of Tenth Century Europe points to this site at http://www.bioc.cam.ac.uk/uto/howe.html that does just that. The point of the article seems to be to point out that scribal errors down a manuscript stemma show a remarkable similarity to mutations down a DNA string over time. Interesting, but who knows what it means.

The problem of course is that it assumes that the more copies a text goes through the more scribal error there will be. But that isn't the case. Part of the problem in textual criticism is that such assumptions are easily proven false, and one part of the stemma may indeed be very pure, even centuries and multiple copies removed from the the original, while another copy only one copy removed from the original may be rife with errors. In fact, this is just the problem I'm facing right now: I have a mnauscript very close to Aelfric's lifetime that contains many errors, another that is 2 centuries later, and other than updating the orthography into late 12th, early 13th century orthography (the ge- prefix on verb forms in OE becomes an i- prefix for example), is remarkably free of scribal error even though there is active editing of the text (leaving out portions on purpose). That is, the later manuscript, which displays activity that should add a layer of opportunities and situations that give rise to scribal errors is surprisingly free from such errors whereas a manuscript that is supposedly a straight copy and is close to the original has many scribal errors. So far as I know, such an example is not something duplicated in DNA, but I could be wrong, and undoubtedly will be corrected.

3 comments:

Michelle said...

Well, actually in DNA one cell or one individual can go horribly wrong. Hence we have people with Down's syndrome (being a milder form of this type of chromosomal defect) which in effect duplicates a whole 'book' or a large part of a whole book. Like having a copy of Bede's History with two copies of Book 3. Actually more like having an encyclopedia that is supposed to have 23 volumes but has an extra volume 22. There are defects in DNA repair enzymes that cause huge numbers of completely random mutations scattered across the genome. There are two major types of mutations - those that cause a spelling error and those that cause a chunk of 'text' to be added or deleted (sometimes a few words, sometimes chapters worth).

Also, cancer starts in a cell that has accumulated many mutations even though the rest of the cells in the body don't.

On another note, Hebrew texts might be even better for this since, like DNA, they are written without spaces between words or punctuation - just one long stream of letters.

theswain said...

Sure, and that part is true of scribal transmission as well: one scribe may go horribly wrong. Unlike scribal transmission however, if say a person with Downs has a child, that child does not automatically have Downs Syndrome just as a little person, or even 2 little people, can have a child whose height is average. That isn't so of typical transmission of a text: any scribe copying the "defective" manuscript, the horribly wrong one, will copy a defective text and likely introduce errors of his own (barring unforeseen and unusual circumstances) so that the "mutation" if you will WILL (not possibly or have a higher likelihood) be repeated and repeated and repeated. As far as I know, this isn't true of DNA.

I think with your characterization of scribal error as being only two major types: orthographic or addition/deletion of text a gross misrepresentation. For one thing, changing a word for example from "citra" to "circa" is far more than merely a "spelling error" or mistaking an abbreviation (pre- for post-) in the exemplar is again something more than just a spelling problem.

I'm not sure how a text written scriptio continua is necessarily a better model or comparison for what they're proposing than a manuscript written with word spaces is since the model they're proposing has to do with the transmission of the manuscripts rather than the form of the sentence or words: i. e. stemmata of manuscripts containing a text rather than comparison of sentences, clauses, etc. Nor is Hebrew the only language in which scriptio continua practiced, and in Hebrew wasn't practed all that much at all. There's a famous article by Millard that demonstrated that "scriptio continua" in antiquity in Hebrew was not the rule, and in the Square script abjad used in formal texts like Bibles, scriptio continua was not used as shown here in the First Gaster Bible at the BL: http://www.bl.uk/onlinegallery/sacredtexts/gasterbib_lg.html
Note the frequent punctus or spaces between words, and in some cases, different letter shapes indicate word endings.

Michelle said...

What you are describing is the fact that humans (and all eukaryotes) have two copies of every gene and it depends on which copy the child gets from each parent. If they get the mutant copy then they carry the mutation. If its germline there is no way to fix it. Every time a child inherits that copy of that gene they get the mutation. Its just that not every child of that parent will inherit that copy of the gene. However, for many genes this is easy enough to trace.

There are species, such as bacteria, that do not have two copies of every gene and so transmission always effects the offspring.

One 'spelling error' in DNA in the right gene can be fatal to the entire organism. How is that for importance? I don't think scribes were in the habit of throwing away the whole book because one word was defective. Yet, one spelling error in the right gene can be fatal to the organism. It can cause it to abort and never be born, or be born with a fatal disease.

I didn't say there are only two types of scribal error. I said there are two major types of mutations in DNA.