If you were on a selection committee tasked with choosing someone to hire (or to admit to your university, or to receive a prize in your field), and it came down to two candidates who were equally qualified on objective measures, which candidate would you be most likely to choose?

__A) The one who shared your race

__B) The one who shared your gender

__C) The one who shared your religion

__D) The one who shared your political party or ideology

The correct answer, for most Americans, is now D. It is surely good news that prejudice based on race, gender, and religion are way down in recent decades. But it is very bad news—for America, for the world, and for science—that cross-partisan hostility is way up.

My nomination for “news that will stay news” is a paper by political scientists Shanto Iyengar and Sean Westwood, titled “Fear and Loathing Across Party Lines: New Evidence on Group Polarization.” Iyengar and Westwood report four studies (all using nationally representative samples) in which they gave Americans various ways to reveal both cross-partisan and cross-racial prejudice, and in all cases cross-partisan prejudice was larger.

First they used a measure of implicit attitudes (the Implicit Association Test), which measures how quickly and easily people can pair words that are emotionally good versus bad with words and images associated with Blacks vs. Whites. They also ran a new version of the test that swapped in words and images related to Republicans vs. Democrats, instead of Blacks vs. Whites. The effect sizes for cross-partisan implicit attitudes were much larger than cross-race. If we focus just on White participants who identified with a party, the cross-partisan effect was about 50 percent larger than the cross-race effect. When Americans look at each other or try to listen to each other, their automatic associations are more negative for people from the “other side” than they are for people of a different race.

In another study they had participants read pairs of fabricated resumes of graduating high school seniors and select one to receive a scholarship. Race made a difference—Black and White participants generally preferred to award the scholarship to the student with the stereotypically Black name. But Party made an even bigger difference, and always in a tribal way: 80 percent of the time, partisans selected the candidate whose resume showed that they were on their side, and it made little difference whether their co-partisan had a higher or lower GPA than the cross-partisan candidate.

In two additional studies Iyengar and Westwood had participants play behavioral economics games (the “trust game” and the “dictator game”). Each person played with what they thought was a particular other person, about whom they read a brief profile including the person’s age, gender, race, and political ideology. Race and ideology were manipulated systematically. Race made no difference, but partisanship mattered a lot: people were more trusting and generous when they thought they were playing with a co-partisan than a cross-partisan.

This is extremely bad news for America because it is very hard to have an effective democracy without compromise. But rising cross-partisan hostility means that Americans increasingly see the other side not just as wrong but as evil, as a threat to the very existence of the nation, according to Pew Research. Americans can expect rising polarization, nastiness, paralysis, and governmental dysfunction for a long time to come.

This is a warning for the rest of the world because some of the trends that have driven America to this point are occurring in many other countries, including: rising education and individualism (which make people more ideological), rising immigration and ethnic diversity (which reduces social capital and trust), and stagnant economic growth (which puts people into a zero-sum mindset).

This is extremely bad news for science and universities because universities are usually associated with the left. In the United States, universities have moved rapidly left since 1990, when the left-right ratio of professors across all departments was less than two to one. By 2004, the left-right ratio was roughly five to one, and it is still climbing. In the social sciences and humanities it is far higher. Because this political purification is happening at a time of rising cross-partisan hostility, we can expect increasing hostility from Republican legislators toward universities and the things they desire, including research funding and freedom from federal and state control.

Tribal conflicts and tribal politics took center stage in 2015. Iyengar and Westwood help us understand that tribal conflicts are no longer just about race, religion, and nationality. Cross-partisan prejudice should become a focus of concern and research. In the United States, it may even be a more urgent problem than cross-racial prejudice.