James Till was born in Lloydminster, Saskatchewan in 1931. He graduated with a bachelor’s degree at the University of Saskatchewan in 1952 and went on to earn a PhD in biophysics from Yale in 1957. During his studies at Yale, Till became interested in individual cells growing in cell culture. After graduation, he pursued his interest at the Ontario Cancer Institute in Toronto, where he was hired as a postdoc, and spent his first year working with Lou Siminovitch at Connaught Laboratories on “L” cells.
Till met Ernest McCulloch at a party hosted by head of the Department of Medical Biophysics, Arthur Ham, where, after hearing of McCulloch’s interest in doing research on total body irradiation and his need for a physicist to help him, Till volunteered contribute to the study. Till and McCulloch began their research in McCulloch’s lab where they focused on the biological effects of radiation on cancer cells by replacing dead bone marrow cells with healthy cells. They observed that the transplanted cells developed “colony forming units” that proved to be self-renewing precursors of new blood cells, later called a “stem cell.”