Simpson grew up in the Capitol Heights neighborhood, two miles east of downtown Denver. His family moved almost every year to different houses within the area, including 1048 & 1069 Milwaukee St., where his best friend Bob Roe lived at 1110. Bob's sister, Anne, knew Simpson as a child and became his second wife years later in New York. Simpson attended the local grammar school on Columbine, the Presbyterian Church on Fillmore, and East Denver high school before leaving for the University of Colorado in Boulder. Simpson graduated from "East Side High" in 1918 with his yearbook picture captioned, "Knowledge is more than equivalent to force," contrasting presumably his mental stature (large) to his physical size (small). He participated in the senior play and the Forum Debating Society. The high school was relatively large, with 49 faculty and more than 1000 students of whom 263 were in his senior class.


Simpson entered the University of Colorado at Boulder in 1918 and, after three years (with one year off, 1919-1920, because of low finances) he left for Yale for his senior year. In his second year at Colorado, Simpson was the associate editor of a literary magazine, the "Dodo," which he helped start. Simpson took his first courses in geology and paleontology at Colorado; one of his teachers was Arthur Tieje who encouraged Simpson's first interest in geology and paleontology. His grades for 1918-19--English: pass, 90, 94; Algebra: pass, 100; Trigonometry: pass, 99; Analytic geometry: 100; European History: pass, 87, 89; Beginning French: pass, 88, 92; Prose Tales & Stories: 94. For 1920-21--Psychology: 90, 88, 87; Chemistry lect.: 97, 95, 94; Chemistry lab.: 92, 92, 96; Calculus: 97, 100, 100; Physiography: 97; General Geology: 98, 97. For 1921-22--Paleontology: 99, 99, 99; Economic Mineralogy: 94, 92, 96; Crystallography: 97; Gen. Physics: 96, 95, 95; Qualitative Analysis: 92, 87; Geology of Colorado: 93, 95; Geography of South America: 84. In June 1968, Simpson received an honorary degree from the University of Colorado on the 45th anniversary of what would have been his graduating class if he had stayed at the university.


Simpson completed his senior year at Yale in 1923 on a Dana Fellowship. He continued on in the graduate school, earning his PhD in Geology in 1926.He wrote his dissertation on Mesozoic mammals, using the excellent Marsh Collection at Yale's Peabody Museum of Natural History. Simpson secretly married Lydia Pedroja in his senior year, against university regulations. His Yale transcript shows the following courses and grades. For 1922-23--Biology: 95, 95; Economics: 89, 90; French: 92, 98; History: 78, 87; Geology: 93, 96; Reading course with R.S. Lull based on his text,"Organic Evolution": 93, 93. For 1923-24--Field Geology: Honors; Optical Mineralogy: Honors; Petrology: Honors; Paleobotany: 90;Vertebrate Paleontology: Honors; Comparative Anatomy: Good; Embryology: Honors; Vertebrate Morphology: Honors. For 1924-25--Adv. Petrography: Excellent; Problems in Invertebrate Paleontology: Honors; Problems in Vertebrate Paleontology: Honors; Vertebrate Morphology: Honors; Sedimentation: Good; Biological Photography: Honors. For 1925-26--PhD research on Mesozoic mammals. Preliminary exam passed with "distinction."


In the summer of 1924, after Simpson's initial year of graduate work at Yale, he went on his first paleontological collecting trip with William Diller Matthew of the American Museum. They worked Plio/Pleistocene beds in the Texas Panhandle, searching for fossil horses, especially the link between the modern horse and its extinct immediate ancestor. Simpson made his first important fossil discovery on this trip--the head and partial skeleton of Equus simplicidens--which he described, years later, in his book "Horses."


Simpson loved the beauty and solitude of New Mexico, as well as its paleontological prospects. He first visited there in 1924, after the month in Texas with Matthew, collecting for Childs Frick, wealthy amateur paleontologist and museum benefactor. Together with museum preparator Charles Falkenbach, he once again succeeded in finding an unusual and valuable fossil, the skull of the so-called "dog-bear, Hemicyon." A generation later, he worked the early Tertiary strata in the San Juan Basin for a number of years, mostly from 1946 -54. He and Anne had a primitive summer home and field base ("Los Piñavetes") in the mountains above La Jara Valley in the northwest corner of the state where they spent 20 summers and one winter ('51-'52) from 1947-67.


In 1926, Simpson went to the British Museum of Natural History (BMNH) on a post-doctoral fellowship to continue his study of Mesozoic mammals by examining the fossil collections there. His wife Lydia, disliking the London climate, went off to Grasse in southern France with their two young daughters. Simpson thus lived the life of a bachelor, exploring London and the English countryside, often with his sidekick A.T. Hopwood. Simpson returned to the U.S. in late 1927.


In the fall of 1927 Simpson returned to the U.S. from his post-doctoral year at the BMNH and on November 1st became assistant curator of vertebrate paleontology. Simpson enjoyed a long and successful career at the AMNH, with its excellent collections of fossil and living mammals, together with a superb research library. Museum scientists who had an early and important influence on Simpson include W.D. Matthew, H.F. Osborn, and W.K. Gregory. Simpson left the museum in 1959 for the Museum of Comparative Zoology at Harvard University.


Simpson had a life-long interest in South America. In 1930-31 and 1933-34 he went to Patagonia; in 1938-39 to Venezuela with his new wife Anne; in 1954-55 to Brazil and Argentina; and in 1956 to the upper Amazon (Juruá River) where he suffered his near fatal accident. Simpson wrote many articles and several books on his South American travels and research (see esp. 1934, 1948, 1967, 1980, and 1984).


Simpson spent several field seasons in the 1930s searching for early Tertiary mammals in the Paleocene in central Montana, just east of the Crazy Mts. His major publication from this work was on the Fort Union Group that, along with taxonomy and systematics, included paleoecologic and biometric insights that Simpson was to enlarge upon in later writings. The work was undertaken at the invitation of the National Museum in Washington, D.C. to "finish up the work" started by James Gidley who had recently died.


In 1959 Simpson left the American Museum after 32 years, and became an Alexander Agassiz Professor at the MCZ. At the AMNH, he had had a running battle with the administration for several years over just what his responsibilities were, complicated as they were by his slow recovery from the Brazil accident..In 1967 he was appointed to the geosciences department at the University of Arizona, retaining a part-time association with the MCZ until 1970.


Simpson joined the geosciences department in 1967, with a position that would allow him to do just research, with minimum administration or teaching. Despite this freedom, ironically, he had more productive contact with students at Arizona than anywhere else, usually with a weekly lunch group that came to be known as the "Red Fire Balls." Simpson formally retired from the university on his 80th birthday, in June, 1982. Simpson built an annex to his home in Tucson for his office. Surrounded there by his extensive library of books, reprints from colleagues, his private papers, and his many medals and awards as well as space for a part-time secretary, Simpson continued to do his research and writing.