I can't talk or write about the effects of overcrowding on a global scale, because I do not have the benefit of world vision. However, I have had some personal experiences.

I was a teacher in what was euphemistically called an inner city school. I saw the results of overcrowding on a small scale and I believe the impact can be scaled up to city/nation/global levels.

When I first arrived, a new school had just been built nearby to relieve overcrowding. At first, in my classroom, 12-13 students were quite comfortable, relaxed. Lessons took place in a quiet, flexible atmosphere. I knew all the parents and kept in personal touch.

As the neighborhood numbers increased in the apartment buildings, the administration had to add 10 more students. There were some adjustments, some crankiness, some unnecessary pushing and shoving, drawing of boundary lines, but still we were able to cope.

The next 10 (we were now a class of 33) really pushed the boundaries: I had to impose order from above as tempers flared and warfare threatened. These were the same kids, same neighborhood, remember; many of these kids had grown up together. The difference was that there were too many children and limited space and teacher interface time.

Then the final blow. They added 9 more to my class because of restructuring and increased enrollment. I had children sitting at extra side tables and one at my desk. The intensity, the psychological heat, was nearly unbearable and I spent a lot of energy keeping it together. Tempers flared at the slightest provocation; the quiet children became quiescent and compliant, the outgoing children bordered on rebellion, not against me, but against the system that crammed too many children into too few seats.

It was next to impossible to do any good teaching. I was reduced to teaching as teachers must in crowded situations the world over: read the book, learn by rote, recite the answers. I resigned.

All from overcrowding.