PEKING—When most developing nations are worried about controlling the rate of growth of their populations，a group of Chinese social scientists and economists is proposing that China cut its population by at least 30% over the next 100 years.

Tian Xueyuan，an economist at the Chinese Academy of Social Sciences，and other population experts say that China’s optimum population is 650 million to 700 million. The world’s most populous nation currently has about one billion people.