June 5, 2018
Radiocarbon dating is a key tool archaeologists use to determine the age of plants and objects made with organic material. But new research shows that commonly accepted radiocarbon dating standards can miss the mark -- calling into question historical timelines.
Archaeologist Sturt Manning and colleagues have revealed variations in the radiocarbon cycle at certain periods of time, affecting frequently cited standards used in archaeological and historical research relevant to the southern Levant region, which includes Israel, southern Jordan and Egypt. These variations, or offsets, of up to 20 years in the calibration of precise radiocarbon dating could be related to climatic conditions.
Radiocarbon helps date ancient objects—but it's not perfect
"There has been much debate for several decades among scholars arguing for different chronologies sometimes only decades to a century apart -- each with major historical implications. And yet these studies ... may all be inaccurate since they are using the wrong radiocarbon information," Manning said.
"Our work," he added, "should prompt a round of revisions and rethinking for the timeline of the archaeology and early history of the southern Levant through the early Biblical period."
Calibration presents another challenge. With the dawn of the Industrial Age, humans began emitting much more carbon dioxide, diluting the amount of radiocarbon in the atmosphere. Nuclear testing affects radiocarbon levels, too, and dramatically increased carbon-14 levels starting in the 1950s. Modern statistical methods and updated databases allow scientists to take humans’ effects on Earth’s atmosphere into account.
Radiocarbon dating isn’t a silver bullet: Context is everything, and it can be hard to determine if there’s a temporal relationship between two objects at an archaeological site.