حملة البلقان
During World War I, he served in the German army and participated in the Balkans Campaign. In 1924, he received his professorship. After the Nazis came to power he fled to Peru. Between 1924 and 1926 he conducted anthropological research in Central Asia, and later, between 1938 and 1948, in the Andes, and performed and published on self-experimentation in medicine in 1937.