Carbon dating live animal
In principle, any material of plant or animal origin, including textiles, wood, bones and leather, can be dated by its content of carbon 14, a radioactive form of carbon in the environment that is incorporated by all living things.
Because it is radioactive, carbon 14 steadily decays into other substances.
Uranium 234, a radioactive element present in the environment, slowly decays to form thorium 230.
Using a mass spectrometer, an instrument that accelerates streams of atoms and uses magnets to sort them out according to mass and electric charge, the group has learned to measure the ratio of uranium to thorium very precisely.
Dating Subject to Error But scientists have long recognized that carbon dating is subject to error because of a variety of factors, including contamination by outside sources of carbon.
Accurate tree ring records of age are available for a period extending 9,000 years into the past.
Since 1947, scientists have reckoned the ages of many old objects by measuring the amounts of radioactive carbon they contain.
New research shows, however, that some estimates based on carbon may have erred by thousands of years.
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The Lamont-Doherty scientists conducted their analyses on samples of coral drilled from a reef off the island of Barbados.