We don't really know because Dr Calhoun didn't keep research notes or samples, published few scientific papers on his research, never captured or shared signifi

We don't really know because Dr Calhoun didn't keep research notes or samples, published few scientific papers on his research, never captured or shared significant statistical data, had few controls and little regard for cofounds, and almost entirely failed to tell anyone anything about his other "universes". It also doesn't help that the two peer-reviewed studies that tried to replicate his results failed to do so. In many of those experiments the populations reached stable sizes, some without first experiencing a crash and others only after doing so. Some of the loosely-described "aberrant" behavior Calhoun claimed was never observed... not that we can be sure of that because Calhoun never gave us scientifically relevant observations of that behavior, only colloquial descriptions. It seems clear now Calhoun set out to achieve a specific result and worked hard to achieve it. Then people with an ideological axe to grind on all sides fill in the blanks to claim it proves their position. Calhoun for his part went to his grave claiming that mice/rat over-population experiments performed with inbred lab mice strains were in actual fact great models of human behavior and bemoaned that people didn't take his ideas seriously enough by rearchitect society to fit his conclusions.