The Chinese decided that sparrows were devouring their food and began to exterminate them by running after and shouting. The birds got scared, could not sit down to rest and died. After they exterminated the sparrows, the growth of harmful insects began and ate the crop. Because of this, the Chinese began to die of famine. After they bought new sparrows from the USSR and Canada, they began exterminating them again. Also because of starving. You should read about Mao's fucking ideas in general. Grandpa was demented as much as physically possible. And even a little more.