Picture an illustration of the stages of human evolution. It begins with something resembling a chimp dragging its knuckles on the ground, followed by another figure, still much more chimp than man, but a bit less hunched and hairy. And then again, and again, on and on over millennia, until we arrive at homo sapiens—fully upright but etiolated, bald, and flabby.

Not that I’m describing anyone in particular.

We can think of the leadership of the House Republican conference over the past decade similarly.

Evolution in this case begins with John Boehner, an old-guard establishmentarian elevated awkwardly to speaker by a populist Tea Party revolution with which he was never comfortable. Boehner was a party man in the era before Trump, when the GOP was still the political entity to which right-wing voters pledged their highest loyalty. But things had begun to change by the end of his tenure: There was enough populist muscle in the House to pressure him into quitting in 2015.