Political Ideology, Tribalism, and Morality

Here is an article that confirms my thesis that one only feels empathy -- meaning, one only acts morally -- toward those one considers to be in one's tribe. It turns out that knowing someone's ideology affects whether or not you empathize with them. But what does it say that Republicans are slightly less empathetic (96%) toward other Republicans than Democrats are to Democrats (100%), but more empathetic to Democrats (9.5%) than Democrats are to them (0%)? Indeed, politics makes people mean. But this is really only just a particular example of our tribalism.