Animal-derived artifacts

The continuous formation of carbon-14 in the atmosphere and its continuous decay back to nitrogen-14 produces a nearly constant equilibrium concentration of atmospheric carbon-14. That carbon-14 is oxidized to carbon dioxide and then incorporated into plants by photosynthesis. It is also incorporated into animals because animals ultimately depend on plants for food (they either eat plants or eat other animals that eat plants). Consequently, all living organisms contain a residual amount of carbon-14. When a living organism dies, it stops incorporating new carbon-14 into its tissues. The carbon-14 present at the time of death decays with a half-life of 5730 years. Since many artifacts, such as the Dead Sea Scrolls, are made from materials that were once living—such as papyrus, wood, and other plant and animal derivatives—the amount of carbon-14 in these artifacts indicates their age. 

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