Dr. Melvin Calvin, the American biochemist known for the Calvin cycle, was born on this day, April 8, in 1911 (d. 1997). The Calvin cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose. With his colleagues Andrew Benson and James Bassham, they were awarded the 1961 Nobel Prize in Chemistry.

Dr. Calvin was one of four scientists honored with a U.S. Postal Service stamp, in 2011; the Karsh portrait of him features in the background.