As soon as a living organism dies, it stops taking in new carbon.
The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced.
However, the principle of carbon-14 dating applies to other isotopes as well.
Potassium-40 is another radioactive element naturally found in your body and has a half-life of 1.3 billion years.
Libby had first started using the dating method in 1946 and the early testing required relatively large samples, so testing on scrolls themselves only became feasible when methods used in the dating process were improved upon. Davies made a request to date a number of scrolls, which led to a series of tests carried out in Zurich on samples from fourteen scrolls.