Knuckle-Dragging

In a good example of the rhetorical device known as praeteritio, Sarah Palin said of Rick Santorum: "I will not call him the knuckle-dragging Neanderthal. I'll let his wife call him that instead.“

The earliest occurrence I can find of the expression "knuckle-dragging" is Robert L. Humphrey, "Human Nature in American Thought: Reconciliation of the Ages of Reason and Science," Political Science Quarterly 69.2 (June 1954) 266-270 (at 268):

The more primitive the society we visualize, the more easily we can grasp the validity of this phenomenon. Contemplate, for instance, the virtue of hate-fear resultant values and actions for our knuckle-dragging ancestors in their grim, sabre-tooth tiger surroundings.