Over time, carbon decays in predictable ways. And with the help of radiocarbon dating, researchers can use that decay as a kind of clock that allows them to peer into the past and determine absolute dates for everything from wood to food, pollen, poop, and even dead animals and humans. While plants are alive, they take in carbon through photosynthesis. Humans and other animals ingest the carbon through plant-based foods or by eating other animals that eat plants. Carbon is made up of three isotopes. The most abundant, carbon, remains stable in the atmosphere.
The Reliability of Radiocarbon Dating
BioMath: Carbon Dating
The most common of the radioactive dating techniques currently in use involves the isotope 14 of carbon, the radiocarbon. This radioactive isotope of carbon is present in the atmosphere in trace amounts, and in chemical processes is indistinguishable from normal carbon As a result, animal and plant life regularly assimilate carbon 14 atom together with the usual carbon The carbon 14 present in the atmosphere is constantly renewed. The cosmic rays originating from the Sun collide with nuclei in the upper atmosphere and are capable of breaking off individual neutrons.
Radiometric Age Dating
Libby introduces radiocarbon dating In Martin Kamen discovered radioactive carbon an isotope of carbon and found that it had a half-life of about 5, years. Scientists had also found that some of the nitrogen in the atmosphere was turned into carbon when hit with cosmic rays. Thus, an equilibrium was reached, the newly formed carbon replacing the carbon that decayed, so that there was always a small amount in the atmosphere. In American chemist Willard Libby figured that plants would absorb some of this trace carbon while they absorbed ordinary carbon in photosynthesis.
Radiocarbon dating of soils has always been a tricky problem. Since organic matter is continually being introduced into the soil, the measured age of soil organic matter has always tended to underestimate the true age of the soil. Carbon exists in the most part in the isotope C, but has a radioactive isotope, C, with a half-life of years. All terrestrial organisms use carbon dioxide in the atmosphere as a source of carbon, thus there is a constant exchange of C with the atmosphere.