When it comes to determining the age of stuff scientists dig out of the ground, whether fossil or artifact, “there are good dates and bad dates and ugly dates,” says paleoanthropologist John Shea of Stony Brook University.
The good dates are confirmed using at least two different methods, ideally involving multiple independent labs for each method to cross-check results.
Both plants and animals exchange carbon with their environment until they die.
Afterward, the amount of the radioactive isotope carbon-14 in their remains decreases.
This includes factoring in many variables, such as the amount of radiation the object was exposed to each year.
These techniques are accurate only for material ranging from a few thousand to 500,000 years old — some researchers argue the accuracy diminishes significantly after 100,000 years.
Generally speaking, the more complex a poem or piece of pottery is, the more advanced it is and the later it falls in the chronology.
Researchers can measure the amount of these trapped electrons to establish an age.
But to use any trapped charge method, experts first need to calculate the rate at which the electrons were trapped.
Egyptologists, for example, created a relative chronology of pre-pharaonic Egypt based on increasing complexity in ceramics found at burial sites.
Whenever possible, researchers use one or more absolute dating methods, which provide an age for the actual fossil or artifact.