Nowadays, lawyers use a password on a laptop to protect legal documents from fraudsters, but in the olden days, the favored method of anti-fraud protection was a surprising material: sheepskin.
A recent study identified that between the 13th and 20th centuries in the U.K., lawyers almost always wrote on sheepskin parchment. It's not such a surprising fact when you learn that other parchments at that time were typically made of goatskin or calfskin vellum.
How would sheepskin protect legal documents, say over goatskin or calfskin vellum, you might ask?
The team of experts theorizes that it may be because sheepskin's structure makes any attempts of alteration really obvious.
It comes down to fat. In sheep, fat is deposited in between various layers of their skin. When their skin is turned into parchment for writing, it's submerged in lime, which removes the fat and leaves quite wide voids between the layers.
After someone had written on sheepskin parchment, any attempt to then scrape off the ink would make these layers detach from one another — a process known as delamination — and a noticeable blemish would be left behind. It would be crystal clear that someone had attempted to make changes to the writing.
Cattle and goats have a much lower fat density, so these layers wouldn't be so easily delaminated.
Why lawyers wrote on sheepskin parchment
This is the main reason why British lawyers preferred to use sheepskin for legal documents.
Dr. Sean Doherty, an archaeologist from the University of Exeter and lead researcher of the study, said: "Lawyers were very concerned with authenticity and security, as we see through the use of seals. But it now appears as though this concern extended to the choice of animal skin they used too."
The team of researchers from the University of Exeter, and Universities of York and Cambridge, studied a number of historic parchments in order to reach its conclusion.
During their research, the experts found a document written by Chief Justice Sir Edward Coke in the 17th century when paper was more commonly used, who wrote of the importance for legal documents to be written on parchment "for the writing upon these is least liable to alterations or corruption".
So if we want to keep fraudsters at bay, maybe we should go back to writing legal documents on sheepskin parchment rather than hiding them behind passwords on computers. If the experts say so...