The carbon-14 it contained at the time of death decays over a long period of time, and the radioactivity of the material decreases.The approximate time since the organism died can be worked out by measuring the amount of carbon-14 left in its remains compared to the amount in living organisms.
So, every living thing is constantly exchanging carbon-14 with its environment as long as it lives. The carbon in its body will remain until it decomposes or fossilizes.The excavator might employ relative dating, using objects located stratigraphically (read: buried at the same depth) close to each other, or he or she might compare historical styles to see if there were similarities to a previous find.But by using these imprecise methods, archeologists were often way off.Some chemical elements have more than one type of atom. Carbon has two stable, nonradioactive isotopes: carbon-12 (12C), and carbon-13 (13C).In addition, there are trace amounts of the unstable isotope carbon-14 (14C) on Earth. One of the most frequent uses of radiocarbon dating is to estimate the age of organic remains from archaeological sites.