Chairman of the Department of Microbiology for four years. Jerne continued to do work for the World Health Organization as a member of the Expert Advisory Panel of Immunology from 1962 and onwards. In 1966 Jerne moved back to Europe and took up the position of Professor of Experimental Therapy at the Johann Wolfgang Goethe University in Frankfurt. From 1966 to 1969 he was the Director of the Paul-Ehrlich-Institut, also in Frankfurt. In 1969 Jerne again switched jobs, this time to Basel in Switzerland, where he was the Director of the Basel Institute for Immunology until his retirement in 1980. During the 1970s and 1980s, Jerne was a pioneer in the development of immune network theory. According to Jerne's biographer Thomas Söderqvist, Jerne was not a bench scientist, could not pipette accurately, and did not enjoy experimental work. His Nobel Prize was awarded for theories, rather than discoveries. Jerne developed the "natural selection theory of immunology", proposed by Paul Ehrlich 50 years earlier, although he was missing the clonal selection element proposed by David Talmage and then by Frank Macfarlane Burnet. It was met by skepticism among his colleagues at first, James Watson for example told Jerne bluntly that his theory "stinks". Family life Jerne was married three times. He had two sons, Ivar Jerne (born 1936) and Donald Jerne (born 1941), with Tjek Jerne, a painter. Jerne had a third son, Andreas Wettstein, with Gertrud Wettstein, in 1971. According to Söderqvist, Tjek, 35, was distraught when she found out that Niels was having an affair with her best friend, Adda Sundsig-Hansen. Tjek had confided in Adda about her own affairs, and Adda had told Neils about them too. Niels demanded a divorce. Tjek begged him to stay. After he refused, she killed herself. Ivar woke up in the morning, smelled gas, and found his mother dead by the oven. Jerne reportedly treated his second wife like a servant and nanny. He was serially unfaithful to his wives. Awards and honours Marcel Benoist Prize (1978) Paul Ehrlich and Ludwig Darmstaedter Prize (1982) He was awarded honorary doctorates from University of Chicago (1972) Columbia University (1978) University of Copenhagen (1979) University of Basel (1981) Erasmus University Rotterdam (1983) He was a member of Foreign Honorary Member of the American Academy of Arts and Sciences (1967) Member of the Royal Danish Academy of Sciences and Letters (1969) SSI Honorary Member (1970) Foreign