The researchers collected roughly 70-metre core samples from the lake and painstakingly counted the layers to come up with a direct record stretching back 52,000 years.

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.

“If you have a better estimate of when the last Neanderthals lived to compare to climate records in Greenland or elsewhere, then you’ll have a better idea of whether the extinction was climate driven or competition with modern humans,” says Paula Reimer, a geochronologist at Queen’s University in Belfast, UK.

To date the pits, Yoshio Nakamura, professor emeritus of Nagoya University, and Ryo Kondo, director of social education of the education board of the Tokushima prefectural government, both conducted radiocarbon dating tests separately using accelerator mass spectrometry.

Nakano studied 15 pits, and apart from three that could not be analyzed, he concluded that 12 originated from between 135 and 230 A. Kondo studied two others and obtained similar results.

It is one of the few sites around Japan that is believed to be the location of the elusive kingdom of Yamataikoku.

The kingdom appears in “Gishiwajinden,” a history book of ancient China, and is said to have existed from the end of the second century through the first half of the third century until the death of queen Himiko, who co-reigned over a greater nation called Wa, which covers much of today’s Japan.

SAKURAI, Nara Prefecture--Thousands of peach pits found near building ruins in the Makimuku archeological site in western Japan were likely harvested between 135 and 230 A.

D., adding to the possibility that the ancient kingdom called Yamataikoku was located here.

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.

“If you’re trying to look at archaeological sites at the order of 30,000 or 40,000 years ago, the ages may shift by only a few hundred years but that may be significant in putting them before or after changes in climate,” he says.

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