07-02-2023, 05:18 AM
In the early 1960's, John Calhoun did a series of rat experiments looking at fertility and behavior when rats in a confined colony were given free access to food and water. Those experiments are described in Wikipedia under the term "behavioral sink". Rat fertility dramatically fell as the population rose, with a fall happening in parallel with a cultural shift. There was plenty of room for more rats, so it wasn't as simple as not enough physical space. Gangs of male rats came together, there was violent conflict, and others confined themselves to a solitary existence, choosing not to breed. Ultimately all rats died. There are parallels to cultural shifts in human populations today.
"population peaked at 2,200 mice and thereafter exhibited a variety of abnormal, often destructive, behaviors including refusal to engage in courtship, females abandoning their young, and homosexuality. By the 600th day, the population was on its way to extinction. Though physically able to reproduce, the mice had lost the social skills required to mate."
https://en.m.wikipedia.org/wiki/Behavioral_sink
"population peaked at 2,200 mice and thereafter exhibited a variety of abnormal, often destructive, behaviors including refusal to engage in courtship, females abandoning their young, and homosexuality. By the 600th day, the population was on its way to extinction. Though physically able to reproduce, the mice had lost the social skills required to mate."
https://en.m.wikipedia.org/wiki/Behavioral_sink
