Yeah, I too have to take exception to number 5. The problem has never been how many people can physically stand on the Earth (or Zanzibar), but how many the Earth can support. Several groups have tried to estimate the "carrying capacity" of Earth, all coming in at 200 million to 2 billion, depending on standard of living. If a farmer has a field with a carrying capacity of 10 cows, he can raise 10 cows year after year. If he puts 15 cows in the field, it will work for a few years, but eventually all the grass will be eaten down to the roots, and most of the cows will die. Our current population is over 6 billion, and we're eating the grass lower and lower.