The focus on the human  species rather than just the national good is quite new. Leading political thought has only slowly turned from military and economic leadership to develop and protect the people of one country rather than all the people. It required new knowledge in comparative religion an, new awareness of other ways of life as in anthropology, new discoveries in ancient civilizations, such as from archeology. Things like carbon dating have been important. Also theories of biology that connect man to other species, and primate studies that have shown how similar we are (and the hunger for theis knowledge from the vivid interest animal videos on youtube.).