He believed that the forms of social organization including the relations of men and women in different epochs were decided by the stage of development of both production and the family. Women's subordination, Engels argued, had an economic basis. Here he differed from Bebel who had regarded it as partly a result of biology. Engels' interest in origins had a contemporary purpose in contesting the view that women's inferiority was immutable. He supported his theories by drawing on nineteenth-century anthropological work that argued there had been a golden era for women that had been overthrown by men's ownership of private property.