ɪn ɐdˈɪʃən, mˈɔːɹɡən θˈɔːt ðeɪ dɪdnˌɑːt fˈɪt ðɪ ˈɛvɪdəns hiː wʌz fˈaɪndɪŋ ɐmˌʌŋ nˈeɪɾɪv ɐmˈɛɹɪkən səsˈaɪəɾiz ɪn nˈɔːɹθ ɐmˈɛɹɪkə, ɪnwˌɪtʃ hiː hæd klˈoʊsli stˈʌdid sˈoʊʃəl stɹˈʌktʃɚɹ æz ɐn ˈɪndᵻkˌeɪɾɚɹ ʌv stˈeɪdʒᵻz ʌv sˌɪvɪlᵻzˈeɪʃən.
In addition, Morgan thought they did not fit the evidence he was finding among Native American societies in North America, in which he had closely studied social structure as an indicator of stages of civilization.