After holding several teaching positions , he became Professor of the Humboldt University of Berlin in 1955 .
From 1957 he was the assistant to the director of the Institute for Prehistory and Protohistory in the Academy of Sciences .
After holding several teaching positions , he became Professor of the Humboldt University of Berlin in 1955 and from 1957 he was the assistant to the director of the Institute for Prehistory and Protohistory in the Academy of Sciences .