10 Episodes That Should Have Changed Star Trek Forever - But Didn't

9. "Unnatural Selection" (TNG)

The plot of "Unnatural Selection" involves a DNA-altering disease that causes rapid ageing. Before long, the disease has affected the unfortunate Doctor Katherine Pulaski, and the episode becomes a race against the clock to find a cure before the cantankerous doctor succumbs to old age. At the last minute, a potential cure is discovered: by taking a sample of Pulaski's DNA before she had the disease, and using this in conjunction with the transporter, the effects of the disease can be stopped. Naturally, it's a risky procedure, but the crew is out of time and has no other options, so they go with the experimental treatment. Thankfully, it works - but it comes with a caveat. Not only does the procedure eradicate the disease, it reverses its symptoms, reverting Pulaski to her earlier, younger appearance, while retaining her memories. Despite the fact that it all but guarantees long-life (and even possibly immortality,) for some reason the discovery of this fountain of youth is never, ever mentioned again.