“The evolution of cooperation required out-group #hatred, which is really sad,” said Nicholas Christakis, a Yale sociologist
This is just as true on today’s political stage. There are two major parties, and their contests are viewed as zero-sum outcomes.
#Win or #lose.
The presidency is the ultimate example: There are no consolation prizes for the loser.
No researcher argues that human nature is the sole, or even the primary, cause of today’s #polarization.
But savvy political operatives can exploit, leverage and encourage it.
And those operatives are learning from their triumphs in #divide-and-#conquer politics.
Here’s where psychology gives way to political science.
The American political system may cultivate “out-group” hatred, as academics put it.
One of the scarce resources in this country is political #power at the highest levels of government. 
The country has no parliamentary system in which multiple parties form governing #coalitions.
Add to this fact
#redistricting that ensures there are fewer truly #competitive congressional races.
The two parties have inexorably moved further apart ideologically, and leaders are more likely to be punished — “#primaried” — if they reach across the aisle.
And because many more districts are now
deeply red or blue,
rather than a mix of constituencies, House members have fewer reasons to adopt moderate positions.
https://www.washingtonpost.com/science/2024/01/20/polarization-science-evolution-psychology/