Suffering from childhood illness, McIntosh was given a copy of Organic Evolution by paleontologist Richard Lull who taught ay Yale University.
[2] Having finished two years of college, McIntosh was sent to learn meteorology and radar as part of the US Army Air Corps at Brown University, MIT, and Harvard.
A month into his third year of college, McIntosh was called up by the Air Corps and sent over Guam as a flight weather officer in a B-29, also completing 21 or 22 missions over Japan.
Flying in weather planes at altitudes around 32,000 feet (9.8 km), these missions were never badly damaged by Japanese fire, with only rare engine failure leading to landing on Iwo Jima for maintenance.
After the completion of this project in 1953, he remained at Princeton as an Associate Professor, later moving to become chair of the Wesleyan University Physics Department in Middletown, Connecticut where he worked until his retirement in 1998.
In the 1960s he visited Museo de La Plata in Argentina to organize the collections, as well as publishing a catalogue of all the dinosaur specimens at the Carnegie Museum.