The family friends included the ornithologist Edward Saunders and the botanist John Dearness which led to an early interest in birds, plants and fungi.
After studying biology at the University of Toronto, he obtained a B.S in 1909 and started working at the United States Department of Agriculture.
He travelled to France, and in 1919 married the USDA scientific illustrator Mary Carmody, and pursued his research at the European Parasite Laboratory and graduated in 1921 which a doctorate in zoology at University of Paris.
[2] In 1928, Thompson left France and became assistant director of the Imperial Institute of Entomology in Britain, a service he held until 1947 when he returned to Canada.
Historian of science Sharon E. Kingsland has noted that: Thompson believed that all species possessed an essence, or form, in the strict Aristotelian sense, which could not be changed by material means.
He had a strong aversion to the hypothesis that all adapted types had been produced by the random actions of mutation and natural selection.
"[8] Biologist E. S. Russell noted that Thompson treated the philosophy of living organisms from an Aristotelian standpoint.
B. S. Haldane and Ronald Fisher which he believed was too abstract and devoid of common sense and empirical facts.