Dr. Landahl was born in Fancheng, China, April 23, 1913. He obtained his AB (Magna Cum Laude) at St. Olaf College in 1934, the SM (Physics) at the University of Chicago in 1936, and his PhD in mathematical biophysics at the same institution in 1941.

His early professional experience came as an assistant in the Psychometrics Laboratory at the University of Chicago (1937-38), he was an assistant in mathematical biophysics in the Dept of Physiology (1939-42), and a research associate (1942-45),asst. professor (1945-48), assoc. to professor of mathematical biology (1948-58), professor of biophysics (1964-68). Dr. Landahl was secretary of the committee on mathematical biology (1948-64), acting chair (1964-68), also at Chicago. On coming to UCSF in 1968, he was made professor of biophysics and biomathematics, becoming professor emeritus in 1980.

Dr. Landahl was a founding member of the Society of Mathematical Biology, and served as Vice-President (1972-82), and then President (1982- ). From 1973 to 1981 he was chief editor of the Bulletin of Mathematical Biology. He was associate editor of the Bulletin of Mathematical Biophysics, 1950 to 1972. He was a fellow of the AAAS, and a member of Biometric Society, the Biophysical Society, and the New York Academy of Science. From 1962 to 1968 he had a research career award from NIH.

His chief research interests included mathematical biophysics of cell division, nerve excitation and central nervous system; removal of aerosols and vapors by the human respiratory tract, the biological effects of radiation; population interaction; biological periodicities, and insulin production and release mechanisms.