Colbert was born on September 28, 1905 in Clarinda, Iowa to Mary Adamson Colbert and George Harris Colbert, the youngest of their three sons. His father was a school superintendent in
Page County, Iowa before being appointed as a mathematics professor at the newly established Northwest Missouri State University in 1906. Colbert grew up in Maryville, Missouri, where he worked as a paperboy and reporter for the town's
Democrat-Forum newspaper. He also participated in the
Boy Scouts, and became interested in fossils at an early age, collecting shells and corals from nearby creeks. == Early education ==