In the space of another generation, the population of the earth will rise by 2.5 billion. Yet the real problem we face is not so much the increase in numbers as the fact that growth will be highly uneven. Whereas rich countries will see aging populations with little growth, populations in poor countries will double or even triple, having a much higher percentage of young people. Against this backdrop, demographer Massimo Livi Bacci examines the implications of this disproportionate demographic development for domestic social stability, international migration flows, the balance of power among nations and the natural environment. Covering 10,000 years of human history from the Stone Age to the present, Livi Bacci shows how the space available for every inhabitant of the planet has decreased by a factor of a thousand. The notion of limits to the world's capacity - which once seemed a remote matter - is now among the most pressing issues we face, and the need to create effective global mechanisms for sustainable development is now more urgent than ever. An indispensable book for anyone concerned with the moral and political implications of our ever more crowded planet.