Venomous: How the Earth’s Deadliest Creatures Mastered Biochemistry
By Christie Wilcox
Scientific American/Farrar, Strauss and Giroux, 2016
Two-thirds of the way into her new book, just before discussing snakebite necrosis, molecular biologist Christie Wilcox warns us that, “You might want to wait a few hours after dinner before continuing.” I was in fact eating dinner as I read this, but that didn’t stop me from jumping into a Google image search of the damage certain snakes inflict.
I’ve done such searches before, like while reading about the brown recluse spider in Gordon Grice’s The Red Hour Glass. The images of bite-induced necrosis, of flesh that has liquefied and separated from a living arm, leg, torso, or worse, are more vile than anything Hollywood might produce. Red blood is not the hallmark of these wounds. Instead, you see craters of pus and rot, ringed by blackened flesh. And no matter how many times you’ve witnessed these images, a fresh viewing is likely to raise your gorge. Later in the chapter “All the Better to Eat You With,” Wilcox herself mentions recluse bites and the putrid loxocelism wounds they create, admonishing, “don’t Google it…trust me.” This is professional advice worth following, unless of course the body-shock mayhem of John Carpenter’s The Thing gives you a chuckle.
Early in Venomous, Wilcox cops to a lifelong fascination with the world’s deadliest creatures and our interaction with them throughout history. Growing up in Kailu, Hawaii, she began with the alluring Portuguese man o’war—whose sting leaves rippling magenta scars—washing up on the beaches near her home. For her, this book is a love letter to the “fearsome power” and “incredible scientific potential” of animals like jellyfish, scorpions, and the platypus.
Yes, the platypus. The Australian mammal that looks like Daffy Duck in furry drag? It’s the only one of nine venomous mammals that doesn’t bite, but uses ankle spurs to drive away rival males during mating season. Wilcox eases readers into the cruel world of venoms by first acquainting us with this, its most endearing citizen—though the slow loris is pretty darn cute, too. She points to the platypus’ unique physiology to emphasize that
The term “venomous” carries with it an explicit set of requirements. Many species are toxic: they possess substances that cause a substantial degree of harm in small doses (a toxin). We used to think of the terms toxic, poisonous, and venomous as interchangeable—now modern scientists distinguish between them. Both poisonous and venomous species are indeed toxic, for they produce or store more toxins in their tissues. You may have heard that everything is a toxin in the right dose, but that’s not quite true. A large enough dose can make something toxic, but if it takes a lot to kill you, then a substance isn’t a toxin. Sure, you can drink enough cans of Coke for it to be fatal, but sodas are not considered toxins because the amount it takes for them to be toxic is huge (you’d have to chug liters at a time). The secretion of the anthrax bacterium, on the other hand, is a toxin because even a tiny bit can be deadly.
Wilcox does a mostly excellent job bringing her subject to the widest audience possible, which could start with an intensely curious eighth-grader. The brightness of her prose, especially when presenting personal narratives in the vein of science writing’s elder statesman David Quammen (Flight of the Iguana), conjures someone sitting right across from you, whose animated hand gestures bring the animals equally close.
Periodically, however, Wilcox must shift her focus from macro to micro, and as a biochemist her knowledge delves deep. It may challenge casual science readers to keep track, conceptually, of biological components named in rapid succession more for the sake of accuracy than clarity. Here, she explains how Lonomia caterpillar venom can cause victims to suffer hemorrhagic syndrome, which is bleeding from mucus membranes in the eyes and nose and elsewhere:
Lopap, a 185-animo-acid prothrombin activator (named, appropriately, for “Lonomia obliqua prothrombin activator protein”), flies around in the blood setting off the body’s clotting cascade indiscriminately. Meanwhile, Losac (Lonomia obliqua Stuart factor activator), which acts like a serine protease (an enzyme that clips proteins) though it has a different structure, activates another arm of the clotting cascade—factor X—leading to even more clots.
Passages like this, where Wilcox assumes our familiarity with Stuart and X from the biochemistry class we just audited, aren’t too frequent. She does smooth the paragraph’s finish by stating clearly that Lonomia tricks the body into using up its platelets. Without them, clotting can’t happen, thus dramatic blood loss.
If you let the occasional jets of scientific super-speak wash over you, Venomous can offer a writhing bounty of weird—from instances of animals used as murder weapons (by Glenn Summerford, snake-handling preacher), to the concept of self-immunization. The latter is a surreal bit of reportage, featuring Steve Ludwin, college drop-out, musician, and member of a community dedicated to testing the boundaries of how much snake venom the human body can handle. Ludwin met his hero and inspiration, Miami Serpentarium director Bill Haast, when he was nine. Haast, whose facility milked snake venom for research and tourist titillation—until a boy’s death by alligator in 1984 pushed Haast to sell—lived to be 100 years old. The strength of his immune system, be claimed, came from sampling venom judiciously throughout his life, creating in himself a vast array of antibodies. Other contributing lifestyle choices aside, he did survive over 170 snake bites.
Ideally, horses are used to generate antivenoms—which save sting and bite victims in emergencies—because they are large, reducing the likelihood of their own deaths, and they possess so much blood, allowing sizable quantities of antibody serum to be extracted at once. The plot thickens (perhaps curdles, in this case) when Wilcox explains that the short shelf-life of antivenoms limits their potency over time, their production is quite expensive, and other animal proteins frequently cause allergic reactions in the victim.
Human immunity is a frontier worth expanding. An antivenom derived from Steve Ludwin, for example, might cover a wide range of both common and rare snakes, and minimize the side effects incurred by a bite victim he’s saved. Ludwin also says, “I don’t get colds. I don’t get sick. I don’t get the flu.” Wilcox doesn’t mention whether he eats his greens or jogs, but the fact remains that upwards of 100,000 venomous snakebites occur annually, killing about 20,000 people, many in rural or developing areas of the world that lack the medical infrastructure to facilitate saving lives. Any study that can simplify and lower the production cost of antivenoms should be encouraged.
Yet for all of this human effort, animals like honey badgers and the mongoose take their protection against snake venom a step further—and it has nothing to do with antibodies. These feisty mammals have been hunting snakes so long that coevolution has reconfigured their cell structures, or as Wilcox details, “a positively-charged animo acid sits where an uncharged one once did, so the toxins cannot bind.” This, in other words, is a rare case of beneficial mutation.
The quite tasty irony here is that venoms themselves are the result of imperfectly copied genes. Wilcox, scratching the itch of those who, like me, love following evolutionary narrative in any science or nature book, explains that:
Most venoms are thought to have derived from initially small changes and duplications in immune system genes, particularly in the genes for enzymes that fight off infectious disease or parasites. The same kinds of enzymes that break down bacterial walls can create bioactive lipids that turn neurons on or off; the same proteins that rip apart unwanted parasites also tear through a victim’s flesh. It’s not hard to imagine how, over time, these same enzymes, proteins, and other molecules were co-opted to new uses as the opportunities rose.
She finishes by saying that, “just as venom can provide a huge advantage, it also comes at an extreme cost to the animal that produces it.” This goes back to the platypus and his usage of venom during mating-season. The animal’s life has been metabolically tailored—through specific patterns of eating, sleeping, and hunting—by its body’s venom production. The venom in turn benefits passing on selfish genes which, to paraphrase Richard Dawkins’ first book, makes of the platypus “robot vehicles blindly programmed to preserve.”
Though it’s hard to think so harshly of an aquatic mammal, especially one that looks like a middle-aged duckling, Wilcox delivers an example of venom use that feels genuinely malicious. Naturally it comes to us from the insect world, and involves the jewel wasp. This wasp’s venom, rather than affecting the victim’s blood (hemotoxic), goes after the nerves (neurotoxic), and:
The wasp’s stinger is so well-tuned to its victim that it can sense where it is inside the cockroach’s dome to inject venom directly into subsections of its brain. The stinger is capable of feeling around in the roach’s head, relying on mechanical and chemical cues to find its way past the ganglionic sheath (the insect’s version of a blood-brain barrier) and inject venom exactly where it needs to go.
The venom destroys the roach’s ability to respond to questionable stimuli, like human prodding—or the wasp burying it alive and laying eggs on it. At least one of the eggs releases a larva that eats its fill of the still living roach before pupating inside the remains. When its metamorphosis finishes, the new adult wasp breaks free of the thinned-out corpse where it spent half of its life.
Yes, this is the plot of the classic science fiction film Alien. But no, this is not where Wilcox hopes to leave readers in their thoughts about venom and its human applications. Her goal is to highlight the medical potential in learning all we can about these complex, versatile substances. Two diseases we stand to gain advantage over are diabetes and the neurodegenerative Alzheimer’s. A Gila monster peptide called extendin-4 “encourages digestion and the production of insulin,” while also stimulating neuron maintenance and growth. Failing the complete eradication of any one disease, there is pain management to consider.
Thankfully, however, Wilcox closes her debut with a sentiment that doesn’t always grace the pages of science and nature writing. “We can and should conserve venomous species,” she says, regarding record habitat loss around the world, “because they are beautiful and wonderful creatures.” And with a comment aimed at those who would wipe mosquitos from existence, “they are integral to the ecosystems they live in, well-oiled parts of an ecological machine that will break down if bits are lost.”
Keep this in mind, if you’re ever in a semi-lit basement or hiking a wilderness path. From the corner of your eye, you see a recluse, a rattler. They don’t want to waste precious venom on you. But they may just have to.
Ready for dinner, by the way?
Justin Hickey is a freelance writer, and editor here at Open Letters Monthly.