Why were the social sciences dominated by men in the 1800s?

The social sciences were dominated by men in the 1800's because, most simply, all sciences were dominated by men at this time. Men were the fixtures of the academic world, and women at this period were still relegated largely to domestic duties, with some very famous and trend-bucking exceptions. It was not until the women's rights movement of the early 20th century that we began to see a strong expansion of the role of women across the work world, including in academia and research.

During the 1800s century women were expected to live their lives largely home bound, taking care of the cooking, cleaning, and child rearing unlike their male counterparts who spent their time working in factory or socializing with other men in public places, like meetings. It is due to these traditional expectations that women never had the same opportunities for education as men. Therefore, because of the above reasons that social sciences were dominated by men in the 1800s century.