The population of cities exploded, both due to the higher survival rate and migration as rural jobs disappeared. Social mobility all but vanished, as wealth-building required a much higher capital and jobs payed less; however, there also rose a small but prosperous middle class, who were not aristocratic but were not poor either. Low wages and high population led to high crime and disease, but improved sanitation and policing methods increased the ability of the government to combat this. More printing, the advent of statistical analysis, and mass media led to a surge of interest in poverty, and there was an incredible amount of research into the causes of poverty. Charity became fashionable.