Riley Black writes:

No other animal moves the way we do. That’s awfully strange. Even among other two-legged species, none amble about with a straight back and a gait that, technically, is just a form of controlled falling. Our bipedalism doesn’t just set us apart, paleoanthropologist Jeremy DeSilva posits; it’s what makes us human.

There’s no shortage of books that propose this or that feature — tool use or self-awareness, for example — as the very definition of humankind. But much of our supposed uniqueness doesn’t stand up to this tradition. In First Steps, DeSilva takes a slightly different approach. Our way of walking, he argues, set off an array of consequences that inform our peculiar evolutionary history.

DeSilva starts his tour through the annals of bipedalism with other upright organisms. Tyrannosaurus and ancient crocodile relatives are trotted out to show how they moved on two legs, thanks to long, counterbalancing tails. DeSilva stumbles a little here, like arguing that “bipedalism was not a successful locomotion for many dinosaur lineages.” An entire group — the theropods — walked on two legs and still do in their avian guises. But the comparison with dinosaurs is still worthwhile. With no tail, the way we walk is even stranger. “Let’s face it,” DeSilva writes, “humans are weird.” [Continue reading…]