"Trolls are starting to threaten the city." "Well... maybe we can use the stomach acid to destroy traps, and it looks like their liver can be used to make medicine. Lets publish our findings and that'll keep their population in check." ... "Turns out if you overfeed the trolls, they'll vomit up a bunch of stomach acid and pass out, so people have been cutting out their liver and letting their regeneration take care of it. Their population is going up!" "Yep, human greed has doomed us all."