Max Delbrück – Co-founder of Modern Molecular Biology and Genetics

Max Delbrück (1906-1981) Foto: Dr. Ernst Peter Fischer

On September 4, 1906, German biophysicist and Nobel laureate Max Delbrück was born in Berlin. His best known achievement for that he won the Nobel prize was the discovery that bacteria become resistant to viruses (phages) as a result of genetic mutations.

“If you’re too sloppy, then you never get reproducible results, and then you never can draw any conclusions; but if you are just a little sloppy, then when you see something startling, (…) you nail it down (…). So I called it the “Principle of Limited Sloppiness”.
— Interview with Max Delbruck (1978) [9].

Max Delbrück – Youth and Education

Max Delbrück’s father Hans Delbrück was a professor of history at the University of Berlin, and his mother was the granddaughter of Justus von Liebig, the famous German chemist who made major contributions to agricultural and biological chemistry, also often referred to as ‘father of the fertilizer industry‘. The newly discovered quantum mechanics led Delbrück to theoretical physics. Delbrück studied astrophysics, shifting towards theoretical physics, at the University of Göttingen. He received his doctorate in this field in 1929. In the physical field, the Delbrück scattering in quantum electrodynamics (scattering of high-energy photons at the coulomb field of a nucleus via the generation and destruction of electron-positron pairs) is named after him. After several stays abroad, he worked at the Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem from 1932, where he became an assistant to Lise Meitner,[2] who was collaborating with Otto Hahn on irradiation of uranium with neutrons.[3]

From Physics to Biology

At the suggestion of Niels Bohr, he turned here to interdisciplinary work with biology. In 1935, together with the geneticist Nikolai Timofejew-Ressowski and the physicist Karl Günther Zimmer, he published a work on gene mutations, in which they were the first to suggest that genes should be regarded as complex nuclear associations. This was the beginning of modern genetics. By 1937 the political influence on research had become too great; Delbrück initially emigrated to the USA as a research fellow with a Rockefeller Foundation fellowship to research genetics of the fruit fly, Drosophila melanogaster, in California Institute of Technology’s biology department, where he researched bacteria and their viruses (bacteriophages).

Research in Genetics in the U. S.

When the scholarship expired in the autumn of 1939, he received a physics professorship from colleagues at Vanderbilt University in Nashville, Tennessee. From 1947 Delbrück worked at the Caltech again on bacteriophages. In 1942, he and Salvador Luria of Indiana University demonstrated that bacterial resistance to virus infection is mediated by random mutation. This research, known as the Luria-Delbrück experiment, notably applied mathematics to make quantitative predictions. He also soon exchanged information with Alfred Day Hershey. With their investigations, the three scientists laid the foundations for modern molecular biology and genetics, which earned them both the 1969 Nobel Prize in Medicine for their discovery on the replication of viruses and their genetic structure.

In 1949 Delbrück was elected to the National Academy of Sciences, in 1959 to the American Academy of Arts and Sciences. As a biology professor at Caltech (until 1977) he continued his research in several areas. In addition to sensory physiology, the focus was on quantum chemistry and mutations, for example in the fruit fly Drosophila melanogaster.

Return to Germany and Later Years

In 1947 Delbrück travelled to Germany again for the first time, but did not move his centre of life there again. One of his first post-war students in Germany was the geneticist Carsten Bresch. From 1958 Bresch, commissioned by Delbrück, established the Institute of Genetics at the University of Cologne, which had been established by the Cologne botanist Joseph Straub. From 1961 to 1963, Delbrück conducted research at the new Cologne Institute and helped to establish it. This first molecular-genetically oriented research institute in Germany was a model for the establishment of further such institutes. In 1969, he helped the University of Constance to establish its Faculty of Biology. In 1963 he was elected a member of the Leopoldina Society of Scholars and was awarded the Gregor Mendel Medal in 1967.

Max Delbrück was influential in the 20th century’s movement of physical scientists into biology. His inferences on genes’ susceptibility to mutation was relied on by physicist Erwin Schrödinger in his 1944 book What Is Life?, which influenced Francis Crick and James D. Watson in their 1953 identification of cellular DNA’s molecular structure as a double helix. On March 9, 1981 Max Delbrück passed away at age 74.

“The progress of science is tremendously disorderly, and the motivations that lead to this progress are tremendously varied, and the reasons why scientists go into science, the personal motivations, are tremendously varied. I have said … that science is a haven for freaks, that people go into science because they are misfits, and that it is a sheltered place where they can spin their own yarn and have recognition, be tolerated and happy, and have approval for it.” (Max Delbrück, 1978)

Max Delbruck interview with Peter van Zahn (1980, German), [11]

References and Further Reading:

• [1] Justus von Liebig and the Agricultural Revolution, SciHi blog
• [2] Lise Meitner – The Misjudged Genius, SciHi Blog
• [3] Otto Hahn – the Father of Nuclear Chemistry, SciHi blog
• [4] Niels Bohr and the beginnings of Quantum Mechanics, SciHi Blog
• [5] Erwin Schrödinger and his Famous Thought Experiment, SciHi Blog
• [6] Crick and Watson decipher the DNA, SciHi Blog
• [7] Max Delbrück at Encyclopædia Britannica
• [8] Stefanie Tapke. “Max Delbrück – Biographical”. Biographical article. Nobel Media.
• [9] Interview with Max Delbrück, 1978, p. 76-77. Oral History Project, California Institute of Technology Archives, Pasadena, California
• [10] Max Delbrück at Wikidata
• [11] Max Delbruck interview with Peter van Zahn (1980, German), Tobi Delbruck (University of Zurich), Tobi Delbruck @ youtube
• [12] William Hayes (1982). “Max Ludwig Henning Delbruck. 4 September 1906-10 March 1981”. Biographical Memoirs of Fellows of the Royal Society. London: Royal Society. 28: 58–90.
• [13] Ellis E. L., Delbrück M. The growth of bacteriophage. J Gen Physiol. 1939 Jan 20;22(3):365-84.
• [14]  Luria SE, Delbrück M. Mutations of bacteria from virus sensitivity to virus resistance. Genetics. 1943 Nov;28(6):491-511. 
• [15] Peter Fischer Ernst and Carol Lipson (1988). Thinking about science : Max Delbrück and the origins of molecular biology. New York: Norton. 
• [16] N. H. Horowitz (1994). “Review of kay, the Molecular Vision of Life: Caltech, the Rockefeller Foundation, and the Rise of the New Biology”. Biophysical Journal. 66 (3 Pt 1): 929–930. 
• [17] Timeline of Max Delbrück, via Wikidata