Human Errors: An entertaining tour of our body’s many design flaws

Human Errors by Nathan H. Lents

Human Errors (2018), by Nathan H. Lents, is a light, quick tour of some of the ways our human bodies are evidence of poor design, from our weak senses to our way-too-fragile ACL to our seemingly constant battle with back pain. Mostly engaging, often humorous, almost always informative if at times a bit sketchy, Lents does a nice job in conveying the way nature works in not just mysterious but often random ways.

Oftentimes, people mistake evolution and natural selection as a targeted means to an improved end. What Lents makes starkly clear is, based as so much of it is on random mutation, evolution is hardly that. It’s instead a groping forward in the dark, lighting on some changes that are an improvement, but landing as well on others that are anything but. Besides detailing those changes and their impact, he also explains why those detrimental effects were “allowed” to hang around in our species.

One reason, for instance, is that way back in our pre-human (pre-primate, pre-mammal) days, evolution struck on a solution to a problem and just never looked back (often because other changes in bodily form and function made “fixing” things impossible). An example of this is our larynx nerve that could head directly from our voice box to the brain, covering hardly any distance at all. Instead, it loops ridiculously circuitously through our bodies, around the heart, ending up several times longer than it “needs to be.” All because that’s the way it worked in fish. You know, who don’t have any necks. So there you go.

Wonder why your pet never seems to suffer from colds like you do? Turns out because their sinus cavities, like most animals, drain downward, taking advantage of gravity to keep them clear. We, though, have ours drain upward, which seems a little silly. Though not as silly as having a common pathway for our air and our food, as anyone who has ever choked knows. As for those aforementioned joint injuries and back pain, blame that on our bodies not yet having had enough time to fully adapt to a bipedal life system (though we have adapted somewhat, which is why you won’t find knucklewalking or crawling to be a solution to your lumbago). And let’s not even get started on the human reproduction system. After reading Lents’ chapter on this monstrosity of design you’ll wonder how it’s possible any humans were ever born, let alone in such numbers as to overwhelm the planet.

A pleasant surprise in Human Errors is that Lents doesn’t simply stick to the basic body — its skeleton, joints, organs (though, surprisingly, not the appendix), sensory system, etc. — but also includes design flaws around genetic failings, flaws in the working of our brain (false memories, poor decision making), and dietary issues. How, for instance, did we manage to survive when the gene that allowed us to synthesize our own (necessary) vitamin C became broken? Because at that point we lived in an environment that easily provided that essential vitamin via our diet of fruit. But once we expanded our horizons and headed off into less “fruity” spots (i.e. less hospitable to our bodies), we suffered the ravages of scurvy. Thanks to agriculture and then modern technology, we now can easily compensate for our inability to make our own vitamin C, just as technology has allowed us to overcome many of our design flaws (consider how the rate of childbirth mortality for both the child and the mother has plummeted over time). Ironically, however, technology also has at times contributed to our dietary pitfalls, as when polishing rice (white rice) removed an essential B vitamin, though we didn’t realize it at the time (once we found out, we fixed that problem so that the ensuing disease — beriberi — became rare in developed countries).

It’s all very clearly and concisely laid out, whether Lents is explaining how evolution prizes short-term gain over long-term gain, why cephalopods have a much more logically designed eye than we do, or why we make some truly dumb decisions. He maintains a light, conversational tone throughout, and while he can be funny, the humor almost never feels forced. And he is careful to regulate his tone so it matches his subject, dropping the humor, for instance, when he discusses some of the more horrific auto-immune diseases that plague our species. While Lent’s prose doesn’t shine, it’s more than adequate to his purpose, is as noted always clear, and moves along smoothly.

My only complaint about Human Errors is that, at times, I found myself wishing we had spent a bit more time in an area, had delved more deeply into the why’s and how’s. That said, any book that covers so many topics in such an interesting fashion that it leaves you wanting to research more on the topic on your own is a successful popular science book in my mind. Easy, therefore, to recommend it.