The carbon-14 it contained at the time of death decays over a long period of time.By measuring the amount of carbon-14 left in dead organic material the approximate time since it died can be worked out.The results showed that Ötzi died over 5000 years ago, sometime between 33 BC. Uranium has a very long half-life and so by measuring how much uranium is left in a rock its approximate age can be worked out. Love-hungry teenagers and archaeologists agree: dating is hard.The high levels of protein found suggested that the person buried under the car park had eaten a large amount of seafood around the time of his death – and because fish absorb carbon-14 at a different rate to land-animals, the date of death was revised to be sometime between 14.Radioactive dating is a method of dating rocks and minerals using radioactive isotopes.There's a small amount of radioactive carbon-14 in all living organisms.When they die no new carbon-14 is taken in by the dead organism.
Researchers from the University of Leicester have confirmed that the body found buried under a car park in the city is that of 15th-century English monarch and Shakespearean villain King Richard III.While an organism remains alive, the ratio of carbon-14 to regular carbon-12 within it will stay roughly constant.After it dies, the carbon-14 will undergo radioactive decay, and, without any way of replacing it, the proportion of it will decrease.This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks. Some do not change with time and form stable isotopes (i.e.those that form during chemical reactions without breaking down).