Recognizing the continuity of evolution also makes clear the futility of selecting any particular time period for human harmony. Why would we be any more likely to feel out of sync than those who came before us? Did we really spend hundreds of thousands of years in stasis, perfectly adapted to our environments? When during the past did we attain this adaptation, and how did we know when to stop?

If they had known about evolution, would our cave-dwelling forebears have felt nostalgia for the days before they were bipedal, when life was good and the trees were a comfort zone? Scavenging prey from more-formidable predators, similar to what modern hyenas do, is thought to have preceded, or at least accompanied, actual hunting in human history. Were, then, those early hunter-gatherers convinced that swiping a gazelle from the lion that caught it was superior to that newfangled business of running it down yourself? And why stop there? Why not long to be aquatic, since life arose in the sea? In some ways, our lungs are still ill suited to breathing air. For that matter, it might be nice to be unicellular: After all, cancer arises because our differentiated tissues run amok. Single cells don’t get cancer.