Robert John Evans was born on March 18, 1909 in Logan, Utah to Robert James and Alice Hazel Stallings Evans. He attended schools in Logan, and then moved with his family to Lehi, Utah during high school. After graduating he attended Brigham Young University, where he ran for the track team. A member of the Church of Jesus Christ of Latter-day Saints, he served a mission to South Africa between 1929 and 1932. After his return he attended Utah State Agricultural College, where he earned his bachelor's degree in chemistry and mathematics, and a master's in poultry science. He continued his studies at the University of Wisconsin, earning his Ph.D. in the field in 1939. He returned to the West, working at Carbon College in Price, Utah and at the State College of Washington in Pullman. In 1941 he married Alice Pugmire, and they had two children.

In 1947, Evans took a position on the faculty of the Poultry Department of Michigan State University. He completed some advanced studies at Cambridge, England and Edinburgh, Scotland, but remained at Michigan until his retirement in 1977. He was internationally recognized as an expert in protein biochemistry, doing extensive work with eggs and beans.