What aspects of 19th-century life were instrumental in bringing about the advent of Realism?
The Realist movement followed both the American Renaissance and Transcendentalist periods. Given that both periods highlighted individualism and spirituality, the authors of the Realist period focused more upon the problems of society as a whole (and not the individual).
One of the aspects of 19th century life which was responsible for the bringing about of realism was the Civil War and the years following the war. Realists, therefore, did not try to hide life as it was. Instead, they wrote with an objective and unbiased pen. Given that they wanted to depict life as it was, they did not tended to stay away from the heavy handed imagery of the Romantics.
The Realists, driven by what was happening around them in society (racism, slavery, civil wars, and prejudice) wished to show life using realistic settings with dialogue true to those they wrote about.