https://www.youtube.com/watch?v=0Z760XNy4VM In the early 1970s, animal behaviorist John Calhoun built a "mouse utopia" to see what would happen if he created the perfect world for mice, with unlimited food, starting with four males and four females, that could reach a population of 2500. What happened next is absolutely astonishing. When the mice had nothing to do and nothing to work for, their society collapsed upon itself. Females stopped caring for their young. Betas began guarding the elite females, despite them not breeding with anyone. Fights broke out for no reason whatsoever. Mice stopped eating. Their population peaked at 2200, and then died off extremely quickly. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1644264/