an interesting thing to note with regards to human population is that US birth rates are at an all time low (since records have been kept). In fact, in nearly all developed countries, birth rates are below replacement levels.
We talk of controlling population as a way to reduce consumption, but it seems the developed world has voluntarily begun that process, although it is likely for other reasons.
I think that we will need to find a way to reduce consumption per capita before we begin to see real momentum towards sustainability.
$.02
