News Anthropology Rare books covered with seal skin hint at a medieval trade network Cistercian monks in France protected their tomes with furs from faraway marine mammals This medieval book, kept at the Médiathèque du Grand Troyes in France, is wrapped with seal skin. Though the book's cover is now worn, it may have been much furrier in its heyday. É. Lévêque By Alex Viveros 13 seconds ago Science is helping researchers judge books by their covers — and revealing surprising beneficiaries of medieval trading routes in the process. Dozens of rare, fur-covered volumes from 12th and 13th century French monasteries are wrapped with seal skins that may have come from as far away as Greenland, researchers report April 9 in Royal Society Open Science. The findings challenge the assumption that the books’ makers used only locally sourced materials and suggest that they were part of an extensive trade network. Sign up for our newsletter We summarize the week's science breakthroughs every Thursday.