Humans are the only known species to go to war.
Wrong, wrong, wrong. Colonies of ants go to war all the time. Have you ever heard of the Soldier Ant?

More importantly:
To poopman: establishment education? What, so you believe in Time Cube or something? Look, it doesn't make the laws of physics wrong if the so-called establishment teaches them.
To Thatperson: Reducing immigration isn't going to help anything. Most of our population increase comes from people who are already in the nation. Most of the population is congregated in small clusters in different parts of the country, with thousands upon thousands of square miles in between. All we need to do is start building in those areas.

Furthermore, humans have been able to raise their carrying capacity through technology, but that only goes so far: when we breach it, people are going to die. I'd say about 30% of the world's population will remain, at best.