What's fascinating is the the Rat Utopia[0] experiment in overpopulation from the late 60's that Dr. John Calhoun ran.
As a result, more than fifty years ago, on tape, Dr. John Calhoun made some eerily accurate[1] extrapolations of where human population is going to be now, and how our TFR (total fertility rate) would collapse (which they basically are, particularly since Millennial & Gen Z generations).
[0]https://en.wikipedia.org/wiki/Behavioral_sink
[1]https://www.youtube.com/watch?v=iOFveSUmh9U "John B. Calhoun Film 7.1, (NIMH, 1970-1972)"
Since nobody pointed that out yet: rat utopia results are questioned now, based not only on a fact that the enclosed space where rats resided were sitting in direct spotlight, but also on a replicability issue. An experiment with results that couldn't be replicated should be dismissed.
It's entirely possible that the mice in this experiment were overheated, and dominant males didn't fight to "stay in solitude" but rather to be out of direct sunlight.
That's to say, if the cause for such mouseslaughter really was in the temperature, climate change could make original experiment relevant again.