Living organisms and some geological features absorb stable carbon-12 and radioactive carbon-14, which are present in the air in a well-known ratio.This is part of the carbon cycle - the recirculation of carbon through the oceans, atmosphere, plants and animals.The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.This restriction extends to animals that consume seafood in their diet.Since then, the amount of water only fills a bathtub, but one drop of red ink continued to fall into the bathtub each year.With so little water to dilute the red ink, the water’s pinkness steadily increased, but not indefinitely. Because each molecule of this imaginary ink has a half-life of 5,730 years, a point was reached when as many molecules of red ink disappeared each year as fell into the bathtub. The Radiocarbon Revolution Since its development by Willard Libby in the 1940s, radiocarbon (14C) dating has become one of the most essential tools in archaeology.Radiocarbon dating was the first chronometric technique widely available to archaeologists and was especially useful because it allowed researchers to directly date the panoply of organic remains often found in archaeological sites including artifacts made from bone, shell, wood, and other carbon based materials.
Regardless of the particular 14C technique used, the value of this tool for archaeology has clearly been appreciated.After another 5,730 years only half of those 50 (or 25 carbon-14 atoms would remain.) Think of the red ink molecules slowly disappearing at the same rate.One day, about 5,000 years ago, most of the water suddenly drained from the pool.Desmond Clark (1979:7) observed that without radiocarbon dating "we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation." And as Colin Renfrew (1973) aptly noted over 30 years ago, the "Radiocarbon Revolution" transformed how archaeologists could interpret the past and track cultural changes through a period in human history where we see among other things the massive migration of peoples settling virtually every major region of the world, the transition from hunting and gathering to more intensive forms of food production, and the rise of city-states.However, as with any dating technique there are limits to the kinds of things that can be satisfactorily dated, levels of precision and accuracy, age range constraints, and different levels of susceptibility to contamination.