Pleistocene mammoth bone from La Brea Tar Pits of Los Angeles, California. Age: 12,200 ± 35 years
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The information you provided seems to be the age of a Pleistocene mammoth bone found in the La Brea Tar Pits of Los Angeles, California. The age stated is 12,200 ± 35 years. This suggests that the bone is estimated to be around 12,200 years old with a margin of error of 35 years.
To determine the age of such a find, scientists use a method called radiocarbon dating. Radiocarbon dating is based on the fact that all living organisms contain a small amount of a radioactive isotope of carbon known as carbon-14. When an organism dies, it no longer takes in new carbon-14, and the existing carbon-14 in its remains steadily decays over time. By measuring the ratio of carbon-14 to stable carbon-12 in a sample, scientists can estimate how long it has been since that organism died.
The accuracy of radiocarbon dating is enhanced by comparing the ratio of carbon-14 to carbon-12 in the sample with that in the atmosphere. This is because the ratio of carbon isotopes in the atmosphere has varied slightly throughout history due to factors such as changes in solar activity and the Earth's magnetic field. By calibrating the radiocarbon dates using known atmospheric variations, scientists can improve the precision of the estimated age range.
In the case of the Pleistocene mammoth bone from the La Brea Tar Pits, researchers likely collected a sample from the bone and performed radiocarbon dating analysis. The reported age of 12,200 ± 35 years reflects the estimated age based on this method, taking into account the margin of error.
It's worth noting that radiocarbon dating is just one of many techniques scientists use to determine the age of ancient fossils. Other methods include uranium-lead dating, argon-argon dating, and thermoluminescence dating, among others. By employing various dating techniques and cross-referencing their results, scientists can build a more comprehensive understanding of the age and history of the specimens they study.