> Left on their own in nests subject to invasion, nursing females attacked their own young
>Procreation slumped, infant abandonment and mortality soared.
>Lone females retreated to isolated nesting boxes on penthouse levels. Other males, a group Calhoun termed “the beautiful ones,” never sought sex and never fought—they just ate, slept, and groomed, wrapped in narcissistic introspection. Elsewhere, cannibalism, pansexualism, and violence became endemic.
>On day 560, a little more than eighteen months into the experiment, the population peaked at 2,200 mice and its growth ceased.
>A few mice survived past weaning until day six hundred, after which there were few pregnancies and no surviving young
>The mice had lost the capacity to rebuild their numbers—many of the mice that could still conceive, such as the “beautiful ones” and their secluded singleton female counterparts, had lost the social ability to do so
>In a way, the creatures had ceased to be mice long before their death—a “first death,” as Calhoun put it, ruining their spirit and their society as thoroughly as the later “second death” of the physical body.
This reminds me a lot of Japan, and the MGTOW movements that are growing in the west and that have been established in Japan for some time, especially the "beautiful ones"