 Benson was born on September 24, 1917, in Modesto, California, the son of a rural physician of Swedish immigrant stock.He studied as an undergraduate and masters student at the University of California, Berkeley, where he learned optics from Luis Alvarez and worked in the chemistry lab of Glenn T. Seaborg.In 1942, he received his Ph.D. from the California Institute of Technology; at Caltech, he worked under the supervision of Carl Niemann, conducting experiments on the fluorination of thyroxine; his later thesis work concerned "periodate and lead tetraacetate degradation of its vicinal amino glycol".