atavistic

The crisis alongside the Texas border is just the latest instance of Republicans looking back to the Antebellum era for precedents to justify their increasingly atavistic behavior.

The forward-facing, commercial ethos of the old GOP would have to accommodate itself to the atavistic, Lost Cause-nostalgia of the American South.

Yet that does nothing to diminish the totemic power they wield over us, which is an expression of the unquestioned, atavistic nature of belief.

How far has the Republican Party fallen into atavistic tribalism?

Depending on your perspective, this is either heartening or, at a time when the trend seems to be toward mutually agreed-upon porous borders on sexual fidelity, atavistic.