Start Carbon dating is flawed

Carbon dating is flawed

The technique hinges on carbon-14, a radioactive isotope of the element that, unlike other more stable forms of carbon, decays away at a steady rate.

(Carbon dating is already limited in scope because older artifacts have to be dated using other methods.

For instance, Lucy, the 3.2-million-year-old human ancestor, was dated by scientists who studied the volcanic flows and ashes in deposits where her bones were found.)“Given current emissions trends, fossil fuel emission-driven artificial ‘aging’ of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected,” Graven wrote.

Preserved leaves in the cores — “they look fresh as if they’ve fallen very recently”, Bronk Ramsey says — yielded 651 carbon dates that could be compared to the calendar dates of the sediment they were found in.

The recalibrated clock won’t force archaeologists to abandon old measurements wholesale, says Bronk Ramsey, but it could help to narrow the window of key events in human history.

As a rule, carbon dates are younger than calendar dates: a bone carbon-dated to 10,000 years is around 11,000 years old, and 20,000 carbon years roughly equates to 24,000 calendar years.

The problem, says Bronk Ramsey, is that tree rings provide a direct record that only goes as far back as about 14,000 years.

Archaeologists vehemently disagree over the effects changing climate and competition from recently arriving humans had on the Neanderthals' demise.

The more accurate carbon clock should yield better dates for any overlap of humans and Neanderthals, as well as for determining how climate changes influenced the extinction of Neanderthals.

Marine records, such as corals, have been used to push farther back in time, but these are less robust because levels of carbon-14 in the atmosphere and the ocean are not identical and tend shift with changes in ocean circulation.

Bronk Ramsey’s team aimed to fill this gap by using sediment from bed of Lake Suigetsu, west of Tokyo.

Since the 1940s, scientists have used carbon dating to determine the age of fossils, identify vintages of wine and whiskey, and explore other organic artifacts like wood and ivory.