Today we are experiencing an era of global demographic revolution, when humanity is moving to limited reproduction. Why is this happening and what does this greatest event lead to? Not only the distant future depends on the answer to these questions, but also the approach to solving today's problems, in particular to analyzing the causes and consequences of the global crisis. In the book, in a form accessible to non-specialists, the famous scientist sets out his demographic concept, explaining the ongoing processes, reflects on the fate of the world and the challenges facing humanity.