(Human Errors, Nathan Lents, May 2018)
To Err is Human
Human Errors is a page-turner of a biology book. Nathan Lents focuses on mistakes, redundancies and weaknesses that make life a constant gamble for humans. From genetic code destruction to pointless bones, overtaxed muscles, meandering nerves and backward designs, the book combines a million years’ worth of wrong choices, errors, flukes and plain bad luck that is the human body. At several points, Lents ventures that no engineer would design such and such a system this way — it’s just wasteful, inefficient or crazy.
The human body is the sum of all its travels through time. It has vestiges of other forms it took, corrupted DNA that was not immediately fatal (so it was able to be passed on) and evolutionary benefits that have outlived their usefulness. The result is a being that needs an outsized amount of care and feeding, technology and medicine. We are the only animal with this need.
-Our sinus cavity drainage (from the top!) gives humans headcolds far more often than any other animal.
-Our backs are optimized for four-legged living.
-Human eyeballs are built backwards, causing a large blindspot in each eye that is more or less overcome by having two eyes and therefore stereo-vision. Cephalopods got our kind of eye right, among the two dozen totally different kinds of eyes, each adapted to the bearers’ environment.
-Our procreation equipment is so inefficient, both mother and child are at risk of death from the act of birth, unlike any other primates. Lents says primates will continue to care for other offspring while giving birth, something unimaginable for women. Cows often barely notice they are giving birth.
-There is an entire a la carte menu of autoimmune diseases unique to humans, and often only to women, for which we have no cures and no idea why they occur. Our own cells attack our systems until they kill us. Another unique feature of humans.
One recurring theme is food. We are both blessed and cursed with the need for a variety of food. Most animals eat the same thing day in and day out all their lives, but have finely balanced metabolisms, because they produce whatever they need internally. Humans need constant interventions with different vitamins, minerals and meds. That humans could subsist and thrive on multiple foods started out as a giant Darwinian advantage. Now that we actually need that variety for a balanced diet, it is a liability. We are the only animal with this need, too. Our DNA is so corrupted we now require this variety and intervention — or die.
Our failing DNA gets its own chapter. The GULO gene in humans is the stub of something that was once very useful. GULO produces vitamin C — just not in humans. Somewhere along the way, an ape had a gene mutation that disabled GULO. It must have lived in an environment filled with citrus, because it didn’t die off, but produced offspring that also had the gene disabled. As animals dispersed from those food sources, scurvy killed off those who had no access to citrus. Today, we have vitamin supplements and imported fruit all year. Lents says our bodies will simply never be able to accidentally repair and restore what’s left of GULO to active duty. There are now too many missing factors for such a complex mutation to occur.
“You cannot have sexual reproductions, DNA and cellular life without also having cancer,” Lents says. It is a natural bug in our design. He says there is a 100% chance of developing cancer if something else doesn’t kill you first, because “cell division is a dangerous game” and innumerable mutations can trigger uncontrollable tumors.
As he says in the epilogue: “It’s survival of the fittest, not the perfect.”