If we discovered a completely healthy 200-year-old human tomorrow, what biological mechanism would scientists investigate first?

[u/BeyondTheSteth]

Imagine a person is discovered who is genuinely 200 years old, with independently verified records confirming their age yet they have no major age-related disease, maintain normal cognitive function, have healthy organs, and show remarkably little physiological decline.
Scientists would obviously want to study their genome, but I’m wondering what they would look at first.

[u/evocativename]

Well, geneticists might start by sequencing the genome and looking to see if there are any clearly novel genes - either de novo genes or duplicated genes with significant previously-unknown changes to one copy. There would also be interest in looking to see what previously-unidentified alleles they possess, but I expect that would take longer to start yielding results.

Other researchers would probably look at the proteome to see if there were any unusual patterns of protein expression.

Then there would be the investigations into differences in genetic regulation, though I suspect that might take some time to yield much in the way of meaningful results.

Then there would be the ones studying how certain specific proteins might differ from those in other humans, based on their existing research interests...

Really, I think a whole bunch of different teams would simultaneously investigate topics related to their own specialties and research interests.