By George W. Sledge, Jr., MD
My wife and I were walking after dark on a sidewalk near our home. Suddenly—and suddenly is the word—we both stopped. A few feet ahead we saw the sinuous form of what, in the dark, seemed to be a snake. But it wasn't, as a few seconds perusal confirmed. Instead, it was the husk of some plant, or rather two husks which had fallen close to each other, and which our brains had interpreted as a snake. There is something curious about two people in Palo Alto, neither of whom had seen a snake in years, simultaneously imagining one out of some dead plant parts.
Yet this is what we are programmed to do. There is something in evolutionary biology called the Snake Detection Theory, which suggests that the threat of snakes played an important role in the creation of the primate brain. Our distant primate ancestors, swinging through trees, safely above the level of most other predators, were still easy pickings for whatever boa or viper happened by. Early detection of snakes was a potent driver of survival of the fittest.
Or so the theory goes. And it seems a pretty good theory, as pretty much every primate species has the ability to identify snakes almost instantaneously, including humans. Far faster, indeed, than our ability to recognize other dangerous predators.
Seeing those non-snake husks flooded my brain with memories of snakes past, memories I had not accessed in decades. Late in my teens, my family moved into a new home in a suburban development surrounded by empty, open fields. When we moved in, the lot next door was basically reclaimed Midwestern cow pasture. One early evening, as my father and I stood outside, a small, innocuous-looking garter snake wandered out of the next-door lot onto our driveway.
My father, the calmest human I've ever known, immediately freaked out. He ran into our garage, pulled out a garden hoe, and proceeded to club the poor creature to death. I tried to talk him out of it. Garter snakes are hardly dangerous. They eat bugs, not suburbanites. But to my dad, who had grown up on a farm in lowland North Carolina, this was something primal, something he just had to do. It was the only time I can ever remember him losing control.
Looking back, it's clear to me that the monkey brain part of my dad was experiencing fear of that poor little non-venomous creature. Fear of snakes is exceptionally common, occurring in as many as half of humans. It doesn't appear to matter if you grew up in the Bronx or in the Appalachian Mountains; fear of snakes is incredibly common. Then there is ophidiophobia, a true paralyzing phobia around snakes. I don't think dad had that, but it was something close. Fear, as all know, is the father of hatred.
And then another memory, close on to the first. I trust this one a bit less, so feel free to consider this a (potential) tall tale. Once, while visiting relatives in North Carolina as a young child, my uncle took his sons, my brother, and me along to property he had near a lake. To get to the lake, we traversed dense sodden undergrowth in a dark forest. My uncle, a very tough guy, led the way. At one point he stopped, yelled “stand back," and stamped his foot down. And then—and here is where I do not know if this is real or manufactured memory—he leaned down and cut off a snake's head with a machete. “Water moccasin," he said, matter-of-factly, threw the head and tail in different directions, and on we went. The story seems so preposterous that I hesitate to share it, but the memory is strong. All I can say is that, if it had been me leading the way, I would have run screaming in the opposite direction had I seen a water moccasin. They are nasty, dangerous creatures.
My wife and I got talking about this and she immediately came up with three more snake stories from her younger years. I suspect that this is something commonplace, this memory for snakes. I've never been harmed by a snake, in contrast to dogs (dog bite), cats (cat scratch), bees (bee stings), or mosquitoes (too many bites to count, though no malaria or West Nile virus yet), but snakes somehow stick in one's memory like almost no other animal. And I still love dogs.
If you live in the United States, it is hard to die of a snake bite. On average around 7,000-8,000 people per year receive venomous bites, of which only about five die. Crosswalks are far more dangerous, with more than 6,500 pedestrian deaths per year. And many snakebite deaths appear readily avoidable. Wikipedia (what did I do before Wikipedia?) has a page devoted to snakebite deaths by decade.
The last decade includes descriptions such as “[Name] was bitten on the right hand during a service at his Full Gospel Tabernacle in Jesus Name church" and “While camping at Sam A. Baker State Park in Missouri, [Name] walked outside, saw a snake, and brought it to his son's attention. When he picked it up, the snake bit him." Note to self: don't pick up venomous snakes. And then my favorite: “He was likely killed by one of the 24 venomous snakes he kept in his home." Addendum note to self: don't fill house with potentially lethal animals.
But outside the United States the story changes. The World Health Organization estimates that some 5.4 million people are bitten per year, and that around 81,000 to 138,000 people per year die of snakebites. And the deaths are not the whole story: irreversible kidney failure, permanent disability, and limb amputation occur at 3 times the death rate. Unsurprisingly, the toll of snakebites is greatest among agricultural workers in low- and middle-income countries, and children are particularly vulnerable. The victims are precisely those unlikely to have access to hospitals and antivenoms. Snakes still exert Darwinian pressures in the modern world.
You might think that snake venom would be a good source of novel therapeutics. And yet, perhaps because medicinal chemists are smart and don't like handling poisonous snakes, you can only point to a very small number of medicines derived from snake venom, and only one of these (captopril, the first ACE inhibitor) can I ever remember having prescribed to a patient. I cannot find any evidence that a snake venom derivative has ever been used for cancer, though an interesting recent paper suggesting a possible COVID-19 application. Alas, vaccines, monoclonals, and Paxlovid appear to have cut off the path to FDA approval for this promising agent. Or the researchers got snake-bit and left the field.
Finally, of course, there is the snake as symbol. In Judeo-Christian mythology, snakes are evil, starting with Eve's interaction in the Garden of Eden, but also in phrases such as the Psalms' evil men who “make their tongue sharp as a serpent's, and under their lips is the venom of asps." In the New Testament, the Pharisees are called a “nest of vipers" because of their hypocrisy. Snakes get a lot of bad press in the Bible, and this has reverberated throughout Western culture. Shakespeare's Macbeth, for instance, is full of snake imagery.
And snakes get a bad rap in common culture. We refer to someone as a snake in the grass, or say that another is a rattlesnake, or that a vicious person is full of venom, or that a particular office environment is a real snake pit, or that some con man is a snake oil salesman. The only relatively kind cultural reference for snakes that comes to mind is the feather boa worn as a fashion accessory, and even that doesn't give me positive feelings about boa constrictors, who I can easily imagine choking the life out of me. In contrast, while I wouldn't want to go mano-a-urso with a grizzly, I have no trouble calling someone a big teddy bear as a sign of his essential sweetness.
Or, if you need further evidence of how the world thinks about snakes, look at an endless stream of “B" movies. Here I reference Tubi, my favorite online source of guilty pleasure trashy movies, with names and thumbnail sketches: Venomous, wherein “a virus transmitted from snakes mutated by a terror attack on a government lab brings on a quarantine as the snakes have come above ground to attack"; Snake Outta Compton, in which “a rap group…is a city's only hope in a battle with a giant mutating snake monster"; Snakes on a Train (enough said); King Cobra (“30 feet of pure terror"); Python, where “a military cargo plane carrying a smart, prehistorically massive python crashes in suburbia"; and finally, Boa v. Python, because apparently python alone wasn't enough. In contrast, put “cows" into Tubi's search box and you get Village of Smiling Cows and The Moo Man.
One of the interesting things about these movies is not just that snakes are dangerous, but that they have the power to transform. In Snakeman, a research group searching for the fountain of youth in a jungle stumbles across its giant guardian snake, whose venom transform its victims into (you guessed right) snakemen. The movies in which people are transformed into snakes are numerous: 7th Voyage of Sinbad, Conan the Barbarian, The Golden Child, and Night of the Cobra Woman, among many others. These movies, in turn, reflect an ancient tradition of snakes as transformative creatures, the shedding of skin symbolizing the potential for regeneration and immortality.
Indeed, many ancient cultures revered snakes as religious icons. Basmu was the ancient Mesopotamian fertility goddess. The Norse had Jormungandr, whose venom does in Thor during Ragnarok, the Scandinavian doomsday. The Egyptians had no less than five snake deities: Wadget, Renenutet, Nehebkau, Meretseger, and Apep.
While some of these were scary deities (don't ever, ever mess with Renenutet, who breathes fire and can still the hearts of men with a single glance), Wadjet is the guardian of children and childbirth, and Meretseger is the goddess of mercy, though she did apparently take a dim view of grave robbers. Good folks, anyway, Wadget and Meretseger. The world was full of snake-like divine beings revered by this or that religion: you respected snakes in the old days, even as you bowed before them and feared them.
And then, of course, there are the Greeks. Unlike Basmu, Meretseger and Jormungandr, who retain few worshippers, the Greek view of snakes continues with us to this day. Medusa, whose hair was replaced with venomous snakes, could turn one to stone if you stared into her eyes, which put something of a damper on her social life. Amazon Prime is running a Medusa commercial, including Nicki Minaj lyrics, in which the ancient turn-them-to-stone curse is lifted through Medusa's purchase of stylish sunglasses from Amazon Prime. A television commercial celebrating a two-and-a-half millennium-old myth is immortality of a sort.
But doctors everywhere are linked to ancient Greek snakes through the rod of Asclepius, the Greek god of medicine who is instantly recognizable through his rod, a snake-entwined staff. That symbol is now the global symbol for medicine, included in the logos of health organizations everywhere, such as the World Health Organization, the American Medical Association, and my own Stanford University School of Medicine.
The origins of the Rod of Asclepius are hidden in the distant past, but in the healing temples of ancient Greece (called asclepeions) non-venomous snakes slithered freely through the dormitories where the sick and injured slept. I'll leave you, dear reader, with that vision: imagine yourself rounding some morning in an asclepeion. Wear high boots and bring a rod. And remember that we in the medical profession honor the old ways, snakes and all, even as we create the new. Someday my snake will eat your crab, cancer.