In 2000, scientists proposed finding bacteria that eat a certain chemical by feeding them the compound tagged with radioactive carbon - 13. (sciencemag.org)
But the atmosphere keeps making more radioactive carbon, and none of that gets into the plant after it dies. (religion.blogs.cnn.com)
Those changing levels of radioactive carbon could be used to estimate when individual cells in the body, and in the heart, arose. (scientificamerican.com)