It is argued by, among others, Stephen Pinker in his book The Better Angels of Our Nature that one of the sources for reduced rates of violence over the past several centuries has been that modern media, something which has been on the rise since the Gutemburg press was invented, fiction and much nonfiction alike extolls us to put ourselves into other people's shoes and therefore come to appreciate the world from their perspective. In contrast, historically we were unable to do this because modes of mass communication were very limited and most space was reserved for religious purposes. True interpersonal understanding was therefore limited to close acquaintances and was therefore primarily present only for family and friends. And it has indeed been scientifically shown that while only people in some cultures, i.e. advanced ones, display universal sympathy towards the suffering of anyone, all cultures display sympathy towards family and friends. This latter tendency makes evolutionary sense because it protects those individuals with whom you share the most DNA or else with whom you have the greatest symbiosis. If Pinker were right, it would be logical to suppose that modern morality is the result of an innate instinct for compassion for those closest to you expanding into compassion for all of humanity.
OF course, mass media can be used to dehumanize strangers as well as to humanize them. In this former capacity, it was largely responsible for much of what was worst with fascism and communism. However, especially as of late, the dehumanizing form of mass media seems dead and gone in most places at most times. Western Europe is now the most peaceful place in all of human history, with homocide rates as low as 1/100,000 and no internal wars.