A scientific technique for estimating the age of very old objects. It is based on the principle that all living organisms exchange carbon with their surroundings. They intake sugars and starches as food, and exhale carbon dioxide. The concentration of the isotope of carbon, carbon-14, should be exactly the same in a living organism as the concentration in its surroundings. As soon as an organism dies, it ceases to exchange carbon with its surroundings. The radioactive carbon-14, which has a half life of over 5000 years, slowly decays. The age of an artifact can therefore be estimated by comparing the proportion of carbon-14 its body contains, as opposed to the proportion currently living organisms contain.

This method does have flaws. For example, if the proportion of Carbon-14 was ever much higher or much lower, for whatever reason, this would skew the results. Also, researchers have fed mice diets which contained only carbon-12, so when the mice died and were carbon dated, their ages were estimated at several thousand years.