"Behavioral sink" is a term invented by ethologist John B. Calhoun to describe a collapse in behavior which can result from overcrowding. The term and concept derive from a series of over-population experiments Calhoun conducted on Norway rats between 1958 and 1962. In the experiments, Calhoun and his researchers created a series of "rat utopias" – enclosed spaces in which rats were given unlimited access to food and water, enabling unfettered population growth. Calhoun coined the term "behavioral sink" in his February 1, 1962 report in an article titled "Population Density and Social Pathology" in Scientific American on the rat experiment. He would later perform similar experiments on mice, from 1968 to 1972 and results were the same in 4 generations of mice and rats they stopped reproduces and all died out.

There are examples of human settlements going though the same Extinction paradox in Eastern Island the island was heavily forested and had enough resources to sustain a large population. However the settlers of Eastern Island over populated and used up all the resources to they turned to cannibalism to when discovered were only 100-200 people left out of the 10-20,000 that where there the previous generation.

Today we see this happening all over the world in Europe birth rates have dropped to a small percentage it was before and other parts of the world including Japan. The Japanese have lost all sexual appetite and birth rates are next to nothing as article 10 years ago "No Sex Please We're Japanese. https://www.bbc.co.uk/programmes/b03fh0bg

So in 4 generations we had the Boomer that populated the world from 1 billion to 7 billion when all generations before never exceeded 1 Billion for thousands of years. Generation X born in the 70s & 80s started to slow the population explosion to 2 children for 2 adults on average. Then we have the Millenial generation that are barely reproducing focusing on careers and trying for a family much later if at all is under world census birth rates are only 1 child for every 4-5 adults on average. https://www.nytimes.com/2021/05/05/us/us-birthrate-falls-covid.html This will make the 4th Generation the apply named Generation Z the Last Generation when all the previous generations die out of old age in 60-70 years population will be down by 1/5th 1.2 billion or less and infant mortality rates on the rise and people dying before they have children at higher levels with the ever growing gender disparity between men and women over equality. We could see the end of the Human Race in 80 years. https://youtu.be/gjCGapvmSbY

Well we had a good run guys!