# How to identify the age of a "living" person?

An Indian old man claims he is [180 years old] now.

We are not able to tell he is 180 or 181 probably. But can we tell he is 90, 120, 100 or 150?

Different people may age differently.
A 60-year old person may appear to be 80, while somebody else could appear younger than their mathematical age. Some other people may have progeria.

What is the most accurate way to identify a living person's age nowadays? Are there reliable parameters to measure?

C-14 needs a long time base line. Hence, it is suitable for the bone of dead people.

What kind of method can guarantee it can distinguish a 30y and a 80y old person? What's the error bar of that method?

• Cut off a limb and count the rings Aug 5, 2015 at 13:24
• possible duplicate of Can we determine a person's age by dating methods or other means?
– AliceD
Aug 5, 2015 at 14:22
• Birth certificate, I presume :P Aug 5, 2015 at 14:31
• @WYSIWYG By the way, a person celebrates his/her birthday on the correct day only for (max) 4 years after his/her birth. Aug 7, 2015 at 5:24
• You have the wrong impression about carbon-14 dating, the long time horizon doesn't have anything to do with not being able to use it to date the age of a living organism. Living things are constantly replenishing the very limited supply of carbon-14 while they are alive. It is only after the organism dies that the carbon-14 clock starts to tick. A dead organism no longer replenishes its supply of carbon-14 and the carbon-14 it did have begins to decay into nitrogen-14. We can then measure the percentage of carbon-14 left in the remains and date them to when they died.
– AMR
Dec 24, 2015 at 4:53

The most accurate method known so far may be Horvath's methylation dating algorithm, which uses 353 CpG sites (Genome Biology research article, Nature news article).

From the Nature article, this method was validated with at least one population.

[After the publication in Genome Biology] Marco Boks at the University Medical Centre Utrecht in the Netherlands applied [the algorithm] to blood samples collected from 96 Dutch veterans of the war in Afghanistan aged between 18 and 53. The correlation between predicted and actual ages was 99.7%, with a median error measured in months.

However, I did not read the original research article and it seems that the dating method works poorly on cancer patients.

• DNA methylation is susceptible to environmental factors. Aug 5, 2015 at 14:31
• Good article. This may replace teeth as the gold standard. Aug 5, 2015 at 18:45
• @anongoodnurse, I was actually hoping someone would argue that dating using teeth would be the best way to estimate the age, since I'm not familiar with this literature. Aug 6, 2015 at 9:29
• @Jonathan - See the possible duplicate. I think it's close. I almost posted an answer, but the Nature article surprised me. Plus, you don't need to pull a tooth. Aug 6, 2015 at 14:36
• My question is about the error bar in fact. Look at the boldface sentence please. Dec 23, 2015 at 13:06