What do you think caused the large indentation in the 50-54 age bracket in germany's 1997 population pyramid?

Mao's policy of commune farming 
1959-1961 
The famine triggered by the "Great Leap Forward" was one of the largest man-made disasters in human history. Estimates of the number of casualties vary greatly and are difficult, if not impossible, to verify. Conservative estimates assume that from 1958 to 1961, over 14 million people died of starvation, and the number of reported births was about 23 million fewer than under normal conditions. Other authors have estimated the number of famine-related death of up to 30 million or higher