I recently took a longer look at Mouse Utopia and was not too impressed: https://www.gwern.net/Questions#mouse-utopia It's very confusing what it actually showed. For starters, there's no such thing as the 'Mouse Utopia'; Calhoun ran dozens or scores of related experiments, it seems, and only very briefly and cursorily described a few of them at different stages in a handful of publications, which are about the only source for all discussions of 'Mouse Utopia'.