system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Can anyone explain to me how Dr. McCoy could possibly be 137 years old in Encounter At Farpoint?

I get that they wanted one of the original stars to be in the pilot of Next Generation, I also get that in the star trek universe, medicine has come a long way. But I don't ever remember any actual explanation of how he was still alive, or for that matter, why he was touring the Enterprise -D at all.
gpt
137 really didn't that old. We have a people living to 100 all the time now, and even a few making it up to 115-120. 

400 years(from now until TNG) to learn how to increase possible life expectancy by 30% isn't unrealistic at all. And remember, it was only McCoy touring. He and Uhura are both still alive and old, but the others have long since departed for the, ahem, final frontier. 

And I've seen articles indicating that we'll see someone hit 130 probably in the next 50 years. We're eating better, excercising better, and medical science is really making some breakthroughs in aging.