There is a growing tension between two apparently irreconcilable trends: (1) demographic projections that world population size will reach 10 to 11 billion by the middle of the next century; and (2) scientific estimates that the Earth's long-term sustainable carrying capacity (at an “adequate to comfortable” standard of living) may not be much greater than 2 to 3 billion. It is past time to develop internationally coordinated sociopolitical initiatives that go beyond slowing the growth or stabilizing global human numbers. After “inescapable realities” that humans must soon confront, and notwithstanding the considerable difficulties involved in establishing “global population optimums,” I conclude with several suggestions how best to bring about a very significant reduction in global population over the next two to three centuries. These proposals are cautiously optimistic.

This article outlines a consistent and rational model for solving ethnic conflicts. We argue that ethnic separation should be regarded as an alternative to national unity, and not simply dismissed as impossible. A decision on separation or unity should be made democratically by the group whose separation has been proposed. If separation is approved, migration over the border between the newly formed states should be part of such a solution. The article has three main parts: (1) a model for solving separationist demands; (2) an analysis of the evolutionary background to ethnic conflicts; and (3) a discussion of principal objections to the proposed model. The present international impotence in situations of ethnic conflict is to a high degree caused by seeing most solutions as impossible—either realistically or morally. This article stresses the virtue of having one model instead of the “flexibility” that currently prevails under the disguise of generally acclaimed, but contradictory ideals.