Most of the evolution that shaped the primitive brains of our prehuman ancestors into the linguistic, symbolic, neurotic modern brains that serve us (sometimes poorly) today took place during the Pleistocene, an epoch which began about 1.8 million years ago and only ended ten thousand years ago. During that period—and in a few isolated places, still to this day—our species made its living as hunter-gatherers, and it was the demands of that lifestyle that sculpted the minds we have today.
