First Steps: How Upright Walking Made Us Human, by Jeremy DeSilva is an eminently readable non-fiction work. I read through it in as single sitting, propelled forward by DeSilva’s prose and enthusiasm, and I was captivated throughout, as well as ending up much better informed about our species’ evolution and bipedalism (along with learning why I’ve ended up with so many sprained ankles, inflamed Achilles, bad knees, and a bad back).

DeSilva is a paleoanthropologist, but more than that, he’s an expert in the foot. More than that, he’s an expert on the ankle. If that sounds an absurdly narrow focus, I’ll let him explain it:

We are trained this way [hyper specialization] because paleoanthropology is a science of fragments. In six weeks at a fossil site, we may find a couple of hominin teeth, and if we are lucky, a hominin elbow here and a foot bone there. To make sense of these ancient bits of bone, we learn everything we can about how one bone differs among different kinds of animals, how those differences affect the way an animal lives, and how that bone has evolved throughout ape and human evolution. This is what it takes to squeeze every bit of information we can out of the precious hominin scraps we find.

And when he says “scraps” he means it. Or as he quotes one fellow researcher slight exaggeration, “you could toss all of the evidence for the origins of upright walking into a shopping bag.” To which DeSilva appends, “and still have plenty of room for the groceries.”

As you read DeSilva’s accounts — some second-hand, some first-hand — of how some of the most important discoveries were made, you’ll first marvel that we have even that paltry number of bones, and then marvel all the more at just what scientists like DeSilva are able to deduce based on so few “scraps.”

DeSilva divides his book into three large sections: Part 1 explores what we know or guess about the origins of bipedalism in humans, Part II looks at how that ability led to us “becoming human” as well as propelled us (literally) out into the wider world, and Part III looks at the impact of bipedalism on how we live today, including the benefits — physical, mental, emotional — of walking, as well as its downsides: dangerous births, all those pesky ailments noted above.

After a relatively quick tour through millions of years (ancient crocodilians, dinosaurs, giant walking kangaroos) and evolution’s several (often failed) attempts at bipedalism, we arrive at the primates and our own ancestors, along with a number of theories about why we hominins started to walk upright. These include the “peek-a-boo” theory (standing to “scan the savanna for predators”), standing to “look large and threatening” (something you’re still told to do if you encounter a mountain lion or grizzly), the “low-hanging fruit” theory (pretty self-explanatory), the “monkey see, monkey do” theory where standing up “started as a trend, became culturally cool, and then went viral, eventually leading to gradual anatomical changes”, the “carry” theory (again, self-explanatory), and a number of others.

To narrow the list, DeSilva says it would help if we knew when and where the trait arose, and so after a very easy to understand explanation of the various ways we date fossil finds, we get a tour of major fossil discoveries, such as Lucy (3.18 MYA) and Ardi (around 4.5 MYA), and what their bones can tell us about if they were adapted for walking upright or not. Working back even earlier, we learn of fossil apes that predated hominins and walked upright, albeit in trees instead of on the ground (similar to modern gibbons). Which means, as one researcher told DeSilva’s class: “Asking why humans stood up from all fours is the wrong question . . . Perhaps we should instead be asking why our ancestors never dropped down on all fours in the first place.”

In the ensuing section, we get some fascinating questions about the intersection of bipedalism and tool use, diet, brain growth, and language (such as why walking on all fours makes it difficult to make sounds). DeSilva also traces the radiation outward from Africa and the many hominin cousins wandering around, such as Homo floresienis, Neandertals, Denisovans, and Homo naledi (and probably more). We enter somewhat more familiar territory as we near our own time, and at the start of the final section DeSilva takes us through not how we evolved to work but how we learn to walk (including how the average age this occurs varies according to culture and geography). Of course, before we can walk, we have to be born, and the last section also includes a detailed look at childbirth — why it’s so difficult for humans compared to other primates and mammals, and how some theories that women’s bodies being adapted for childbirth (wide hips, for instance) make them less efficient walkers turn out to be inaccurate. The book covers the bookends of our lives, from birth to death, delving into a number of studies showing how walking can increase our life span, not just generally but also in terms of decreasing the likelihood of dying from specific illnesses, such as breast cancer or heart attacks. After a section on the pitfalls of bipedalism (easier ACL tears, bad backs), DeSilva takes a surprising turn into its impact on our social interactions and our empathy, noting how so many ancient remains show evidence of injuries so severe the individual could only have lived to the age they died at through the assistance and care of others. It’s a lesson in empathy, DeSilva says, we might better embrace today.

As noted in the intro, this was a smoothly readable text. DeSilva’s prose is always smooth, crystal clear, and easy to understand, whether he’s explaining dating techniques, chemistry, finely detailed anatomy, or interweaving timelines. Never once did I have to reread a section to understand it, but just as importantly, never once did I have the feeling of having things completely dumbed down so that was the case. The narrative is methodical and logical, one topic bleeding seamlessly and almost inevitably to the next.

Even better, DeSilva’s voice is lively, engaging, warm, and personal. His love of fossils and science radiates outward from the pages time and again. Here he is, for instance, looking at one of the best-preserved hominin brains ever found: “The anatomical detail is exquisite . . . a thick layer of sparkling calcite. Light reflected from it as if it were a geode. . I hadn’t expected Taung to be so beautiful.” And here, in Nairobi, when he is startled by a Kenyan paleontologist trusting him with “one of the most complete and important skeletons ever discovered” — Nariokotome Boy: “It was like giving curator of the Louvre a list of Renaissance paintings to study and being handed the Mona Lisa. My arms went weak and my hands trembled.” Later, we see his contagious sense of delight and wonder when he and a small team uncover a footprint discovered 40 years earlier, scorned at the time as being a human ancestor’s and then eventually feared lost:

The layer peeled away from the ash.
I have devoted much of my career to studying the evolution of upright walking but had never put my hands or eyes on an actual Australopithecus footprint.
Until then. A chill ran down my spine.

Side by side with his love of discovery is his passion for collaboration, necessary he says to progress in the field — “We need the collective knowledge of the entire scientific community to reveal their [fossils] secrets. The more trained eyes on these fossils, the better.” But he admits, much to his sorrow, “that some discoverers of ancient human and ape fossils restrict access to a limited few in bizarre quid pro quos antithetical to how science should work.” Which is why he is moved when he traveled 4000 miles to meet Madeleine Böhme, a German paleontologist: “I didn’t know Böhme, and she didn’t know me . . . Within minutes though I was surrounded by fossils . . . Böhme loves fossils as much as I do, and she agrees . . . these bones are meant to be shared.”

As is the knowledge of ourselves that comes with studying them. And I can’t think of many who would do a better job of that than DeSilva does here in First Steps. Lucid, fluid, sometimes funny, often fascinating, always informative, warmly optimistic, and filled as all the best popular science books are, with a contagious sense of awe and wonder at rich beauty and mystery of life. I’ve been on a great roll lately with my science reading and First Steps fits right in with those others (Einstein’s Fridge, Life’s Edge and The Zoologist’s Guide to the Galaxy) Highly recommended.