I imagine that the insects lived longer because their body was saying there was something important they still needed to do, which had not yet been done. Their mission in life is to mate and produce children. They hadn't accomplished that mission, and their body knew it, so it kept them alive longer and longer and longer, hoping they would eventually fall in love with some other fruit fly, hoping they weren't the last fruit fly on earth stranded on a desert island needing to fly across the ocean to rejoin all the other fruit flies. Their body assumed that they had accidentally been stranded someplace far away from all the potential mates, and that it must give them plenty of time to keep searching until they found one. Maybe a terrible hurricane blew them hundreds of miles away from all the other fruit flies. Their body said, 'You haven't mated yet, and I'm not gonna let you die until you do, because mating is really, really, really, really important.' It's so important that you can't die until you've done it. It's like their bodies are giving them a chance to mate no matter what it takes. But if they've mated, their body says, 'Ah, everything is okay now. I can finally relax and stop worrying so much about keeping this body in absolutely perfect shape.' So the fruit flies sit back and just let themselves go. They die sooner, because they've achieved their mission in life, and they feel at peace, and they know it's okay to die now.
