I'm reminded of the study that found rats will choose heroin over food, over and over again, until they die; and the follow-up study that compared rats kept in

I'm reminded of the study that found rats will choose heroin over food, over and over again, until they die; and the follow-up study that compared rats kept in isolation (matching the original study) with rats allowed to live more naturally in communities and found that rats living in communities try the heroin but then go back to eating food.