"The Orville" had an episode where an alien culture used a procedure that sampled teeth to determine the exact birthdate of a person. There's not much in the t

"The Orville" had an episode where an alien culture used a procedure that sampled teeth to determine the exact birthdate of a person. There's not much in the tooth apatite that would be useful for radiometric dating on the time scale of a single human lifespan, though. I don't think you could do it with radiometrics, no matter what you sampled. Anything precise enough to indicate one year within a range of 100 would probably kill the animal with its radiation, even if it were naturally common enough to be taken up by living organisms. It may be that a tooth is an easy source of original DNA, and approximate age may be extrapolated from accumulation of copy-error mutations in different types of cells in the body, which would be affected by the frequency of division. So by comparing DNA found in the tooth mineral against that found in the tooth nerve cells, and in the tooth blood supply, it might be possible to narrow the range of possible whole-organism ages by referencing mean mutation rates, and then further narrow it by checking telomere lengths. Seems like that might vary somewhat by individual, and their history of radiation exposure.