Why does science fiction portray extended human lifespans negatively?

So many of our big media stories about living to be over 120 are negative or take place in a dystopia — from Dorian Gray to In Time. Why is that? Sonia Arrison, author of 100+, tries to explain — and predicts that this could soon change.

Arrison talked to Slate as part of their Future Tense series, that has been looking at extended longevity and some of the challenges and opportunities that could result. Here's what she has to say about science fiction's dark view of extended lifespans: