Mutant Maps: Borrowing an Idea from Biology to Enrich History
Weiss, Peter, Science News
In London last month, the numerals 1623 stared out from the title page of a rare Shakespeare book. Printed in a quaint typeface, those digits left no mystery about the publication date of that highly prized volume--which fetched $5.2 million at a Sotheby's auction on July 13. Were publication dates so easy to come by for some other treasures by the Bard and for thousands of other undated books, maps, etchings, and other printed works, many uncertainties in history and other fields might quickly clear up, scholars say.
Hungry for missing publication dates, rare-document specialists scrutinize watermarks, book bindings, and even tiny imperfections in individual letters of old tracts.
"People want to know when ideas were developed. In the history of society in general, dates are important," says S. Blair Hedges of Pennsylvania State University in University Park.
An unexpected inspiration from genetics recently led Hedges--a biologist with a penchant for old books and maps--to develop a new way to sleuth missing dates.
His work indicates that the print quality declines with the steady aging of the blocks and plates used in the printing process, not with how often they are used, as most specialists had suspected. As biologists calculate species ages from the accumulation of genetic mutations, or molecular clocks, Hedges employs a "print clock" His method estimates publication dates with extraordinary precision, he reports, as long as other editions or related documents with known dates are available as guideposts.
There were more than 3 million books printed on hand-operated presses using woodblocks and copper plates from the 1400s to the mid-1800s, and many of those books weren't dated, Hedges notes. "This method could maybe put a date on many of those books," he says.
If verified, "his process would be to bibliography as carbon dating is to archaeology," comments David L. Gants, an old-book scholar at the University of New Brunswick in Fredericton.
Adds R. Carter Hailey, another specialist in old books, at the College of William and Mary in Williamsburg, Va., "Dr. Hedges' approach, if it can be substantiated, is of immense potential value."
WEAR AND TEAR Hedges' work began as a hunch about books that's based on biology. About a year and a half ago, he was examining copies of a 16th-century book of Caribbean-island maps printed from woodblocks. Printers from this era would often use the same woodblock or plate in each subsequent edition of a book.
This book--known as Isolario by Benedetto Bordone--appeared in four editions: three dated 1528, 1534, and 1547, and one without a date. For 200 years, rare-book specialists have been debating when the undated edition was printed.
As Hedges looked at the various editions, patterns of defects in the maps caught his eye. He noticed gaps here and there in lines on the maps. "In the first edition, there were very few. The later-dated editions had progressively more breaks. That's when I got the hunch," Hedges recalls, "I thought these line breaks are kind of like genetic mutations."
In organisms, the genetic code changes haphazardly, or mutates, at random intervals as a result of chemical reactions or other insults, and the resulting mutations in DNA accumulate over time. Biologists can calculate the average rate of mutation over millions of years of evolutionary transformation. They can then use that average to estimate when one species diverged from others.
As Hedges pored over the Isolario, it occurred to him that random defects in wood blocks--like genetic mutations--may also have accumulated over the years at a constant average rate. If so, then bibliographers could exploit that rate to date documents relative to those with known publication dates. "It's the same principle--counting the number of differences," he notes.
Hedges knew that line breaks in old wood-block prints resulted from cracks in the blocks' raised ridges, which produce the lines. …