I tend to think of as a charcater's life expectancy being contingent upon their healthy behaviour in life. So Vaughn was active at 100-plus because he had been a field agent all that time, and the relatively advanced health service of the Fed meant that his earlier Bond-esque fitness really complemented what Federation science could do for him. The same applied to Picard, whose fitness in youth was mentioned on screen (the marathons, for example), which has resulted in science giving him a better old age.
But other characters like Soong or Joseph Sisko weren't top-of-the-line in youth, they probably ate too much unhealthy food, didn't exercise, drank too much, or whatever ... science couldn't repair them in that manner? Of course the ancient admiral in that early TNG episode doesn't quite fit this pattern.
I know this isn't exactly a watertight argument, but it seemed to fit in my mind how people could age in certain ways and others differently.
The only other thought I could suggest was some kind of post-birth genetic enhancement, to ensure that the natural degredation of human bodies and cells don't occur, and that people can therefore live longer, conceive after menopause, etc. But isn't that contrary to Trek's prohibition on genetic engineering? And we still have problematic people like Joseph Sisko and Soong
But other characters like Soong or Joseph Sisko weren't top-of-the-line in youth, they probably ate too much unhealthy food, didn't exercise, drank too much, or whatever ... science couldn't repair them in that manner? Of course the ancient admiral in that early TNG episode doesn't quite fit this pattern.
I know this isn't exactly a watertight argument, but it seemed to fit in my mind how people could age in certain ways and others differently.
The only other thought I could suggest was some kind of post-birth genetic enhancement, to ensure that the natural degredation of human bodies and cells don't occur, and that people can therefore live longer, conceive after menopause, etc. But isn't that contrary to Trek's prohibition on genetic engineering? And we still have problematic people like Joseph Sisko and Soong