比較について教えてください

Strangely enough, gender difference were more extreme in late 19th and early 20th century Western societies,where women were expected to submit completely to male authority ,than they are among most historically known pre-agricultual peoples
whose ways of life resemble those of the late Stone Age ancestors of Western peoples.

than they are among〜の部分は何が比較されてまた何がareの所で省略されてるのでしょうか？