Rare books from medieval French monasteries were wrapped with seal skins, hinting at an extensive trade network across the North Sea.
A team of researchers has discovered that rare books from medieval French monasteries were wrapped with seal skins, which may have come from as far away as Greenland. The finding challenges the assumption that the book makers used only locally sourced materials and suggests an extensive trade network.
The medieval trade network was a vast and intricate system that connected Europe, Asia, and Africa.
Merchants traded goods such as spices, textiles, and metals along the Silk Road, while the Hanseatic League dominated trade in Northern Europe.
The Mediterranean Sea facilitated trade between cities like Venice and Genoa.
Statistics show that by the 14th century, trade had increased significantly, with merchants exchanging goods worth over £1 million annually.
Historical context reveals that the Crusades played a significant role in establishing trade routes between East and West.
Uncovering the Secrets of Medieval Bookbinding
The discovery was made by Élodie Lévêque, a book conservator at Panthéon-Sorbonne University in Paris, who examined 43 rare books from Clairvaux Abbey and its daughter monasteries. The primary covers were found to be made of sheepskin, but the outermost protective cover, known as the furry chemise, was initially thought to be boar or deer skin.
However, when Lévêque compared proteins from chemise samples with known animal proteins using a microscope, she found that they belonged to seals. Further analysis confirmed this finding through DNA comparison with seals, revealing that four of the chemises were genetically similar to harbor seals from Scandinavia, Denmark, and Scotland, while the fifth was genetically similar to harp seals, likely from Greenland or Iceland.
Seal skins, also known as seal fur, are obtained from seals and used for various purposes, including clothing, accessories, and decorative items.
Historically, indigenous communities have harvested seal skins for their warmth and durability.
In modern times, the trade of seal products is regulated by laws and international agreements due to concerns over animal welfare and conservation.
The International Agreement on the Conservation of Seals, signed in 1952, aims to protect seal populations and regulate hunting practices.
A Trade Network Across the North Sea
The researchers suggest that Norse hunters in those regions may have caught seals and brought their skins to northern France through trading routes. The monks may not have known that they were covering their books with seal skins, which would have been a valuable commodity at the time.

The worn, brownish covers of the books may have been furrier and a different color in their heyday, Lévêque notes. ‘At the time, it would have looked completely like a teddy bear, but light in color.‘
A New Perspective on Medieval Trade
This discovery highlights the importance of science in understanding historical trade networks and the materials used in medieval bookbinding. The study challenges the assumption that book makers used only locally sourced materials and suggests an extensive trade network across the North Sea.
The findings also shed new light on the use of seal skins in medieval Europe, which may have been a valuable commodity for both practical and symbolic purposes. As Lévêque notes, ‘I was like, ‘that’s not possible. There must be a mistake,’‘ but further analysis confirmed that the seals did indeed provide the coverings for these rare books.
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