Old wood effect radiocarbon dating
This is a major concern for bone dates where pretreatment procedures must be employed to isolate protein or a specific amino acid such as hydroxyproline (known to occur almost exclusively in bone collagen) to ensure accurate age assessments of bone specimens.
Alone, or in concert, these factors can lead to inaccuracies and misinterpretations by archaeologists without proper investigation of the potential problems associated with sampling and dating.
By comparing the amount of carbon 14 remaining in a sample with a modern standard, we can determine when the organism died, as for example, when a shellfish was collected or a tree cut down.
In contrast to relative dating techniques whereby artifacts were simply designated as "older" or "younger" than other cultural remains based on the presence of fossils or stratigraphic position, 14C dating provided an easy and increasingly accessible way for archaeologists to construct chronologies of human behavior and examine temporal changes through time at a finer scale than what had previously been possible.Further complications arise when the carbon in a sample has not taken a straightforward route from the atmosphere to the organism and thence to the measured sample. 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.To help resolve these issues, radiocarbon laboratories have conducted inter-laboratory comparison exercises (see for example, the August 2003 special issue of Radiocarbon), devised rigorous pretreatment procedures to remove any carbon-containing compounds unrelated to the actual sample being dated, and developed calibration methods for terrestrial and marine carbon. Radiocarbon dating can be used on either organic or inorganic carbonate materials.Shells of known age collected prior to nuclear testing have also been dated ( to ascertain the effects of old carbon (i.e., local marine reservoir effects). However, the most common materials dated by archaeologists are wood charcoal, shell, and bone. In brief, radiocarbon dating measures the amount of radioactive carbon 14 (14C) in a sample.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.Radiocarbon dating is especially good for determining the age of sites occupied within the last 26,000 years or so (but has the potential for sites over 50,000), can be used on carbon-based materials (organic or inorganic), and can be accurate to within ±30-50 years.All animals in the food chain, including carnivores, get their carbon indirectly from plant material, even if it is by eating animals which themselves eat plants.The net effect of this is that all living organisms have the same radiocarbon to stable carbon ratio as the atmosphere.Once an organism dies the carbon is no longer replaced.Because the radiocarbon is radioactive, it will slowly decay away.