‘Snakes and Ladders’ in Paleoanthropology: From cognitive surprise to skillfulness a million years ago

•‘Active inference’ under the free energy principle played a fundamental part in behavioral responses evolving in early Homo, which is overlooked in paleoanthropology.•The hierarchically mechanistic minds of early Homo were biological inference machines that had less generative depth than ours, though greater than that of great apes.•Neurobiological aspects are outlined that likely were involved in the cerebral evolution of generative depth in Homo.•Compared to modern humans, ‘cognitive surprise’ was more tightly bounded in early Homo who was less responsive than us to unorthodox or novel behavior and less likely to copy it.•Stone ‘handaxes’ were outcomes of novel manual behavior that early Homo enacted often spontaneously from 1.76 to 0.1 million years ago but no less often fell into oblivion.•Continual appearances, disappearances, and reappearances of ‘handaxes’ in the Paleolithic record are explicable in terms of early Homo’s scant ability to generate inferences about how continuous reproduction of ‘handaxes’ could offer benefits and increase the chances of survival.