Margin of error in radiocarbon dating
During the lifetime of an organism, the amount of c14 in the tissues remains at an equilibrium since the loss (through radioactive decay) is balanced by the gain (through uptake via photosynthesis or consumption of organically fixed carbon).
However, when the organism dies, the amount of c14 declines such that the longer the time since death the lower the levels of c14 in organic tissue.
Since carbon is fundamental to life, occurring along with hydrogen in all organic compounds, the detection of such an isotope might form the basis for a method to establish the age of ancient materials.
Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.
Adding the margin of error for carbon-14 (in this case, /- 150 years), the archaeologist can give a reliable date range for the bone: 1655-1405 B. A bone found deep in the ground will generally be older than one found close to the surface, for example.
Two bones found in the same archaeological deposit are likely to be the same age.
Voyage into Archaeology Links, articles, and other beginner's resources in archaeology, including a simulation game called "Be a Time Detective." Glossary of Archaeological Terms What is chert? For example, the arrival of sophisticated carbon-14 dating methods in the 1940s caused scientists to revise their interpretation of events in Europe in prehistoric times.
Plants take up c14 along with other carbon isotopes during photosynthesis in the proportions that occur in the atmosphere; animals acquire c14 by eating the plants (or other animals).
This discovery meant that there are three naturally occurring isotopes of carbon: Whereas carbon-12 and carbon-13 are stable isotopes, carbon-14 is unstable or radioactive.