The Great Mouse Utopia Experiment
The great mouse utopia was an experiment that was supposed to see how a society behaves when confined to a specific area. Four mice were put into an environment where they had limited space but they had all the food and water that they needed to survive. The mice started to reproduce until there was around 2200 mice and then within a few generations they all died.
What is interesting is that once the space was filled the behavior that the mice exhibited. They started ignoring their young. They became interested in homosexuality and then they lost interest in sex altogether which is how they all died. They formed gangs and would pick fights with each other even though there was no need since they had all the food and water they wanted. They became self absorbed.
Back in the 1970's there were some people who believed that our population would keep growing until we would not have enough resources to sustain it. However, the data shows that as technology increases the population replacement decreases. All over the industrialized west and in Japan the birth rate is below replacement levels. As the rest of the world catches up technology wise the same thing will happen worldwide.
So why does technology reduce the birth rate? I don't think there's any one answer but I think a huge reason is because with technology, if someone doesn't want to have a child, they don't have to. As a result unwanted pregnacy is way down. I think another reason is lifestyle choices. People don't settle down as early as in previous generations because there are more options available.
There was this argument that access to pronography would increase irresponsible sexual practices and it's interesting that while pronography is widely available, the amount of sex that people are actually having is decreasing. So it's not having the effect that some people warned that it would have.
I don't think humanity is going to become extinct the same way that the mice did in the experiment, but the experiment did show us that extinction will come regardless of whether we have enough resources or not.