 He was unusual among Indo-European linguists of his time in believing that Indo-European should be classified as a branch of Indo-Hittite, with Hittite as a sister language of the Indo-European languages, rather than a daughter language.Warren Cowgill and his twin brother, anthropologist George Cowgill, were born near Grangeville, Idaho.Along with his brother, he graduated from Stanford University in 1952 and received a Ph.D. from Yale in 1957.