Mother Nature Is Trying to Kill You: A Lively Tour Through the Dark Side of the Natural World

by Riskin, Dan

  In fact, that dark night epitomizes what I love most about nature. There I was, outside, with the woman I love, watching silhouettes of my favorite creatures against a backdrop of stars. On the one hand it was totally peaceful—the silence, the cooling wind, the fresh air—but on the other hand I felt defenseless and vulnerable, lying on my back in darkness surrounded by insects, scorpions, and, for all I knew, more cougars. But the way those elements took me out of my comfort zone is a big part of what made that night so special. To me those scary animals are what bring nature to life. Knowing I’m surrounded by animals that could hurt me reminds me that nature’s not weak or passive. It reminds me to respect the natural world.

  Unlike many experiences in nature I’ve had alone, that night was also a special one for Shelby and me as a couple. It was wonderful for both of us to be able to share an experience like that, with the hostility of the creatures in that environment juxtaposed with the kind of relationship the two of us had built. Against a backdrop of wrath, the caring, loving, and patient affection Shelby and I share was even more apparent.

  From an aesthetic perspective, nature’s wrath is a big part of what I think makes it so beautiful, but my poetic thoughts don’t mean crap to any of the animals out there. On a day-to-day basis, that wrath exists because it can spell success for the animals that wield it. One Texas resident, the venomous fire ant, is a perfect example.XI I weigh around 50 million times what a two-milligram fire ant does, but a fire ant can hold its own against me just fine. The bite of a single individual can leave a welt on my skin that lasts for days, but that’s not what scares me about them. It’s the fact that a person never gets one fire ant bite. Fire ants, like most ants, are successful because they deliver their wrath en masse.

  When you accidentally stand on top of a fire ant colony in your sandals, they come at you right away, but they don’t bite you in those first moments. Instead, they invade enemy territory—crawling up your legs by the hundreds. Because of their small size, they’re barely noticeable. But you notice them soon enough, because eventually one of those ants does bite you, and in so doing, releases a smelly chemical into the air that gives everyone else the signal to bite too. As nearby ants bite, they release more of that same stinky chemical, causing others to bite, and so on. Not only that, each ant can bite multiple times. As a result, one minute you feel nothing, and then suddenly every square inch of your legs burns at once. If they’ve gotten far enough up your clothes, you’ll need to drop your pants immediately to get the ants out of there. Despite how socially awkward that might be, you really have no choice.XII

  Once the ants are gone, the bites are just a little itchy and annoying, but over the next few days they grow, until a day or two later the pus-filled welts on your skin are even bigger than the ants that left them.

  Fire ants suck.

  Ant bites are painful, partly because of an acid that ants have in their venom. It’s called formic acid, after the Latin word for ant, formica. Working as teams, injecting their enemies with formic acid, ants have flourished around the world. There are more than 12,000 ant species out there,XIII and the number of individual ants walking around on Earth is almost unfathomable. Biologists have famously estimated that if you took every single land animal out of the Amazon rainforest and put them all on a scale at the same time, about one-third of that weight would be made up of ants and termites.XIV

  One of the Amazonian ant species that would be on that scale is called the bullet ant. I don’t know if it got that name because it’s an inch long, roughly the size of a bullet, or because when it stings you it feels like being shot. Either way, when Shelby was doing fieldwork for her PhD in the Brazilian Amazon, the locals often warned her about bullet ants. They had a different name for them, though: vinte e quatro, or “twenty-four”—apparently the number of hours for which you can expect to be in searing pain after being stung by one.

  There’s an indigenous tribe in the Amazon, called the Sateré-Mawé, that uses bullet ants in a rite of passage for its men. During a ceremony called the tucandeira ant ritual, the young man puts his hands into a pair of ceremonial gloves that look like giant oven mitts woven out of leaves. Each glove is filled with up to three hundred bullet ants, and the man must leave his hands in there for several minutes while he does a ritual dance. The thing with bullet ants is that the pain gets steadily worse after the stinging and climaxes several hours later, so the ritual goes on for hours after the men take their hands back out of the gloves. This ritual starts for men around the age of twelve and may be repeated twenty-five times or more in a man’s life.XV

  The sting of the bullet ant has a pretty solid reputation as the most painful of any insect, but of course the only way you could really know that would be to go out and get stung by as many different kinds of insects as possible. And if you think no one would ever do something like that, you clearly haven’t spent enough time with entomologists.

  Justin Schmidt studies ants and their close relatives, the wasps and bees. Collectively, these three groups of insects are called hymenopterans, and if there’s one thing ants, wasps, and bees are famous for as a group, it’s that they sting. In the course of studying these insects, Dr. Schmidt has been stung many times, but instead of just swearing loudly about it, he’s recorded what each of those stings felt like. The result of his work is the Schmidt Pain Index.

  The Schmidt Pain Index is a list of scores for different hymenopteran stings, describing how painful they are. It goes from one to four, with four being the most painful. The best part about the Schmidt Pain Index is that some of the stings are described almost the way one might describe a wine. For example, the sweat bee, with a score of one, is “light, ephemeral, almost fruity. A tiny spark has singed a single hair on your arm.” The bull’s horn acacia ant, which you may recall from the chapter on gluttony, scores a two and gives “a rare, piercing, elevated sort of pain. Someone has fired a staple into your cheek.” There are a few hymenopterans with a score of four, and the bullet ant is one of them, described as “Pure, intense, brilliant pain. Like walking over flaming charcoal with a 3-inch nail in your heel.”XVI

  In interviews about his list, Schmidt has said that the pain of a bullet ant is the worst of them all, but although the Schmidt Pain Index contains an impressive 78 species, it falls slightly short of covering all 117,000 species of hymenopterans out there.18 So while the bullet ant may well have the most painful bite of any insect, there’s still clearly a world of pain available to any other entomologists looking to have an index named after them. A good starting point might be the enormous, one-and-a-half-inch-long ant Dinoponera gigantea of Brazil, which is not part of the Schmidt list, and whose sting might be even more painful than that of the bullet ant. A medical report from 2005 of a sixty-four-year-old man stung by a Dinoponera ant describes incredible pain (more intense than passing a kidney stone, he said), cold sweating and nausea, a vomiting episode, and an irregular heartbeat. Three hours later, the man passed stool with a large amount of blood in it, having not had any such problems prior to his sting. His intense pain only started to decrease eight hours after he was stung.19 I’m thinking this ant might give a bullet ant a run for its money (but I’m not going to be the person who signs up to compare them).

  As impressive as it is that an ant can make you poop blood, there aren’t any hymenopterans with a venom so powerful that a single sting can be lethal. Some people have allergies to fire ants or honeybees, so complications from those stings can be deadly, but if you don’t count allergic reactions, or swarms of hymenopterans attacking together, the stings of bees, ants, and wasps are mostly just painful. In fact, adding up the jellies, the cone snails, the spiders, the scorpions, and the hymenopterans, you don’t get anywhere close to the number of human deaths that you get from the top killers. None of the venomous creatures I’ve listed in this chapter so far has even made a slight dent in human populations. That changes, though, when you consider the deadliest of all the venomous animals out there: th
e snakes.

  Of the 3,400 or so snake species in the world, only a few hundred are venomous, but a large number of those venomous snakes eat mammals.20 Even though we’re not the mammals that those venomous snakes feed upon, we’re similar enough to the mammals they do eat that snake venoms are often deadly to us too. Combine that with the fact that snakes hide well and strike quickly, and snakes start to look like the poster creatures for this book.

  It’s kind of shocking how many people get killed by venomous snakes. Most deaths happen in poor countries, where people work in agricultural fields without proper footwear, far from sufficient medical infrastructure. Exact numbers are hard to come by because records in those regions are not as well kept as in other parts of the world. To give you some idea of numbers, though, the country of Bangladesh alone suffers roughly 6,000 deaths per year because of snake bites. Worldwide, the estimate ranges anywhere from 20,000 to 125,000 deaths per year.21

  As with other venomous animals, different kinds of snake venoms work in different ways, and any given snake’s venom is a cocktail of different kinds of molecules.

  Some snake venoms simply kill the cells with which they come in contact, causing swelling and blister formation and ultimately causing the flesh to turn black and die. Imagine one whole side of your leg, from your ankle to your hip, with the skin and underlying flesh eaten away chemically. That’s what a bite from a spitting cobra can do. And just in case that doesn’t hurt enough, the bite also contains chemicals that make your body feel intense pain at the site of the injury.22

  Other snake venoms affect the cardiovascular system. Some cause a sudden drop in blood pressure, while others do exactly the reverse, squeezing the arteries around the heart until it can’t beat properly for lack of oxygen. Others affect the blood itself. They might prevent blood from clotting, as is the case with the venom of the copperhead, or they might make the blood inside you clot up into blood Jell-O, as does the venom of the fer-de-lance.23

  Then there are the snake venoms that are neurotoxins. A few pages ago, when we were talking about spider venoms, I mentioned chemicals in your body called neurotransmitters, which your neurons use to send information to other neurons. There are two different ways a snake neurotoxin can screw that process up, but some of them are permanent and others are temporary. This difference is pretty simple: it depends on whether the neurotoxin affects the neurons sending the neurotransmitters or the neurons receiving them.24

  Some snake neurotoxic venoms disrupt the “sending” neurons by destroying the parts of the cell that send neurotransmitter molecules. The damage caused by this kind of neurotoxin is permanent because the neurons never recover. This is what makes snakes like taipans and pit vipers so deadly. Other snake venoms interfere with the “receiving” neurons by sitting on top of their receptors, physically blocking any neurotransmitters that arrive from other neurons. This second type of neurotoxin lasts only until the venom is broken down and moved out of the way by the human’s immune system. Once it’s gone, the neurons can talk to one another again. That means that if a person has been bitten by the right kind of snake, a medical team that knows what to do can bring the victim back from death’s door.

  For example, the bite of a Malayan krait contains neurotoxins that cause paralysis of the whole body. First the person loses the ability to move voluntary muscles, but soon even the muscles around the lungs stop working. That means air is no longer coming into the lungs, so it doesn’t take long for the victim to die from a lack of oxygen. However, because Malayan krait neurotoxin is of that second, reversible type, there is hope for a victim who is lucky enough to get adequate medical care. If air is pumped into that person’s lungs while they’re paralyzed, there’s never a shortage of oxygen, and no permanent damage occurs. So long as the medical staff keeps the patient “breathing,” that patient can fully recover from the total paralysis of a krait bite in just a few days.25

  Because snake venoms work so well on humans, it’s easy to forget that they really aren’t there to hurt us. Snake venoms are primarily there to help snakes subdue their prey. After all, these are animals that don’t have any arms and that hunt other animals that can usually move much more quickly than they can. It’s pretty incredible that an animal like a rattlesnake can catch something as fast as a chipmunk at all. Fortunately for the rattlesnake, though, it only has to hunt successfully a few times each year.XVII

  When hunting, a rattlesnake relies on its excellent sense of smell to find a spot in the forest that small mammals, like chipmunks, have been using as a trail. It would not be very easy for you or me to smell the residue on a branch from the soles of chipmunk feet that passed by four hours ago, but that kind of thing is right up a rattlesnake’s alley. In fact, that’s why they have forked tongues. The tongue comes out, touches different places in the forest, picking up chemicals that might be too heavy to float freely in the air, and then comes back into the mouth and touches sense organs on the roof of the mouth. It’s kind of like when you go through security at the airport and they swab your bag with that little cloth and then put it into the chemical analyzer. Once the snake detects the chemical residues of mammal footprints, it sets up shop, coils, and waits.

  The wait may last multiple nights, but snakes can be patient. They’re cold-blooded, so they use energy slowly. When a chipmunk does finally pass by, the snake strikes out, stabs the small mammal with its hollow fangs, injects it with venom, and then immediately lets the animal go. After all, there’s no sense holding on to a struggling chipmunk, since it might bite in self-defense. If the strike was successful, the chipmunk will be dead in just a couple of minutes anyway. As the chipmunk runs away, the snake slowly uncoils and then follows the scent of fresh footprints. Before long, the snake reaches the dead chipmunk at the end of that scent trail and sets to work eating it whole. None of that would be possible without venom. In fact, the venom even acts as a digestive juice, starting the breakdown of the chipmunk even before the snake eats it, easing the digestion that will take the snake several weeks to complete.26

  When a rattlesnake’s venom enters a chipmunk, it first goes to work on the blood vessels. Within moments, capillaries and small veins near the bite start leaking blood uncontrollably into the surrounding tissue. This results in swelling, blistering, and overall breakdown of the tissue to its chemical components. As the blood carries the venom through the bloodstream, those problems spread to other parts of the body, including the heart.

  Should a human be unlucky enough to step over a log and onto a coiled rattlesnake, the animal might strike in self-defense. The potentially good news is that roughly half of rattlesnake defensive bites on humans are “dry bites,” which means that no venom is injected. Dry bites still hurt because a pair of daggers just pierced your skin, but at least you won’t suffer the chemical onslaught that eats away at your muscle tissues. Rattlesnakes sometimes deliver those dry bites because they’re just trying to get the human to go away. Whether or not they kill the human doesn’t really matter to the snake, so with all things being equal, it’s better to save venom for when it’s needed.XVIII

  To me, the scariest thing about being bitten by a snake is that you can’t tell at first if a snake bite was a dry one or not. The only way to find out is to wait for symptoms. If you’re lucky, the bite wounds swell up and become painful like any pair of deep puncture wounds would. But if you’re not so lucky, well, what happens next depends on which snake bit you, how much venom it delivered, and whether you have access to antivenin. If it is a rattlesnake, and you’re unlucky enough to have received a “wet bite,” you’ll probably still survive, though. The rapid tissue destruction will do permanent damage to the skin and muscles around the bite site, but rattlesnake venom happens to be nonlethal to humans . . . at least most of the time.

  I understand that people want to believe that Mother Nature is looking after them, but how can they reconcile that idea with the existence of jellyfish, cone snails, spiders, scorpions, bees, ants, wasps, and sna
kes? That’s not even starting on the centipedes, stingrays, scorpion fish, lizards, platypuses, shrews, beetles, and bugs that also use venom. If Mother Nature is so loving, why are there so many venomous creatures out there, and why do so many venoms contain chemicals that do nothing other than increase the pain of the victim?

  Some would argue that venoms provide many useful chemicals to scientists trying to develop drugs, and that’s totally true, but I think it’s a stretch to pretend that’s why nature put them there. The fact is, we humans have learned to take advantage of nature in order to thrive as a species. Just as we eat plants and animals that didn’t volunteer for the job, we take apart the venoms that animals use against us. Through science, we can make antivenins, rendering those venoms less deadly, but even more amazingly, we can use venoms to gain access to parts of our own bodies we couldn’t reach before. If you’re making a drug that blocks pain, see what cone snail venoms are doing. If you’re making a drug that can temporarily block nerves, why not look at snake venoms? Venoms provide keys to the locks on millions of molecular machines within our bodies. With venoms we are making drugs that help us live long and healthy lives. Nature isn’t taking care of us. She’s trying to kill us, and we’re taking care of ourselves.

  Animals kill other animals, and there’s no question that they often inflict pain when they do it. Whether it’s physical abuse or chemical abuse, animals give one another a beating out there every single day. But wrath in the natural world doesn’t just happen on the scale of injured, tortured, or even killed individuals. Wrath happens on much larger scales than that. The wrath of nature is strong enough to wipe out entire species at a time, or even groups of species, without so much as a thought.