ɪn nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi hiː wʌz pɹəmˈoʊɾᵻd tə pɹəfˈɛsɚɹ ʌv baɪˈɑːlədʒi æt wˈɑːʃɪŋtən jˌuːnɪvˈɜːsᵻɾi, ɐ pəzˈɪʃən hiː hˈɛld ʌntˈɪl hɪz ɹᵻtˈaɪɚmənt ɪn tˈuː θˈaʊzənd fˈoːɹ.
In 1980 he was promoted to professor of biology at Washington University, a position he held until his retirement in 2004.