This is a column: a lighter piece from the Works in Progress extended universe, designed to be enjoyed in print. If you’d like to opt out of columns, or any other section, you can do so here. Why did the communist regime collapse in the Soviet Union? Why has it survived in China? The answers might surprise you. Explanations for the sudden end of the USSR after seven decades, and the simultaneous dissolution of the country after centuries, are numerous. They are also lacking.