A carbon dating
“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.She will lead efforts to combine the Lake Suigetsu measurements with marine and cave records to come up with a new standard for carbon dating.
Bronk Ramsey’s team aimed to fill this gap by using sediment from bed of Lake Suigetsu, west of Tokyo.Carbon dating the Dead Sea Scrolls refers to a series of radiocarbon dating tests performed on the Dead Sea Scrolls, first by the AMS (Accelerator Mass Spectrometry) lab of the Zurich Institute of Technology in 1991 and then by the AMS Facility at the University of Arizona in Tucson in 1994-95.There was also a historical test of a piece of linen performed in 1950 by Willard Libby, the inventor of the dating method.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.However, radioisotope dating may not work so well in the future.
Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely.
By measuring the ratio of the radio isotope to non-radioactive carbon, the amount of carbon-14 decay can be worked out, thereby giving an age for the specimen in question.
But that assumes that the amount of carbon-14 in the atmosphere was constant — any variation would speed up or slow down the clock.
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.
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.