Radiocarbon dating is a scientific process used to date specimens that were once alive by measuring the amount of carbon-14 remaining within them. This method is effective for dealing with items as old as 50,000 years.
Living things absorb carbon-14, a naturally occurring radioactive isotope. At death, carbon-14 begins to decay at a predictable rate, allowing scientists to determine the number of years transpiring from the time of death to the time of testing. Items from archaeological sites such as charcoal, bone fragments or hides are often subjected to this testing. Accelerator mass spectrometers and liquid scintillation counting machines are used in this process. Results of radiocarbon testing need to be adjusted or calibrated, given that the amount of carbon-14 in the atmosphere has varied over time.