Just a quick thought, (I know the OP was to do with animals) this planet is not run with the 'Ideals of putting mankind first' it is run with the 'Ideals of putting money first' which obvoiusly doesnt work (look at any news channel in any country)...
There has to be a crunch over the next 200-300 years of total change (perhaps another civilization colapse liken to the mayans,romans,egyptians etc)..imo it will be in the next 50 years.
Perhaps 1 day we will have a utopian idealistic world run by intelligence not monetary greed or by 2600 we will have to find new planets to colonize and even then if we have not controlled the growth rate by 7000ad the mass of human tissue would equate to the mass of the known universe.