28 JULY 2017 • VOL 357 ISSUE 6349 347 SCIENCE sciencemag.org
gloss, written in the margins. It is one of the
few books to survive from that time with its
original cover, and is in remarkable condition, Honey says.
Zachs, an honorary fellow at the Univer-
sity of Edinburgh, wanted to know what
kind of animal hide was used to make the
white leather cover of his book, and in 2012
agreed to open the book to investigation
by Collins’s lab. The manuscript became
the centerpiece of the May symposium,
which organizers describe as a model for “a
360-degree study of any book.”
Collins already had developed a method
to identify ancient species by differences in
the amino acid sequences of collagen and
other proteins preserved in fossils (Science,
24 July 2015, p. 372). His team soon real-
ized that the proteins in parchment offered
a new line of evidence about the animals
whose skin was used and about the eco-
nomics of bookmaking in medieval Europe.
“With books, you have year after year of
pristine information about the medieval
world of animal husbandry,” says Stinson,
who collaborates with Collins.
But no librarian would let them snip a bit
of ancient parchment for collagen testing.
“It’s even harder to sample a rare book than
human fossils or teeth,” Collins says.
So Collins’s postdoctoral fellow in York,
Sarah Fiddyment, developed a nondestruc-
tive method to extract ancient proteins from
parchment. Librarians often “dry clean” a
rare manuscript by rubbing it lightly with
a polyvinyl chloride eraser, which pulls tiny
fibers off the page in curled debris that’s
usually swept away. Fiddyment discovered
that the eraser shavings captured proteins
from the parchment, which she could iso-
late and analyze with a mass spectrometer.
She had just developed this method
when Zachs reached out to Collins, and
the researchers applied it to the Gospel
of Luke. They found that the book’s cover
was made of the skin of roe deer, a species
common in the United Kingdom. But the
strap was made from a larger deer species,
either native red deer or fallow deer introduced from continental Europe, possibly by
the Normans after their invasion in 1066.