„In human records, there is no case of an absolutely monogamous society failing to display great [cultural] energy. I do not know of a case on which great energy has been displayed by a society that has not been absolutely monogamous…“

„The whole of human history does not contain a single instance of a group becoming civilized unless it has been absolutely monogamous, nor is there any example of a group retaining its culture after it has adopted less rigorous customs.“

– Dr. Joseph Daniel Unwin