Snake venom is incredibly dangerous, unbelievably complex, medically promising—and the ultimate adrenaline rush. What's not to love?
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It was the last night of a very long week," says herpetologist and molecular biologist Bryan Grieg Fry in his plummy half-American, half-Australian accent, describing the bite he suffered from one of the deadliest snakes on Earth. "Of course it's always the last night. They never get you when you're fresh, and it was a new species, one that we hadn't caught before, and it behaved differently than the sea snakes we were used to." A ridiculously handsome adrenaline junkie, with a snakelike shaved head and sidelines in rock climbing and surfing, Fry is the buoyant 35-year-old deputy director of the Australian Venom Research Unit at the University of Melbourne. In groundbreaking research on the toxic cocktails that squirt out of snake fangs, he has painted a startling new picture of the complexity of venom, especially of its evolution, and he has derived potential new drugs by studying its nightmarish effects on human physiology, occasionally by experiencing those effects firsthand.
In the case of this deadly bite, he and his wife, Alexia, a gorgeous Cate Blanchett look-alike, had flown to Weipa, on Australia's Gulf of Carpentaria, to collect venom samples from a variety of sea snake species, including Hardwick's sea snakes, elegant sea snakes, and rare Stokes sea snakes, which can grow up to six feet long. Because the whole operation involved an awful lot of exposure to awfully dangerous animals—sea snakes are among the world's most poisonous reptiles, and their venom can cause horrible pain, spasms, and the disintegration of muscle tissue, all en route to a quick and ugly death—Fry had taken his standard precautions. He had contacted the head of the local emergency ward, explained what he'd be up to, and packed big syringes full of adrenaline and strong antihistamines.
Then he'd gotten on with having a good time. Standing in the gunwales of a motorboat at nightfall, Fry and Alexia cruised the warm tropical evening and swept the water's surface with handheld spotlights. Sea snakes have astonishing aquatic adaptations, like valved nostrils to seal in air, lungs that can hold a breath for hours, and skin that flushes nitrogen to beat the bends, but they do have to surface to breathe once in a while. When they do, a spotlight will catch a ripple of coils in its glare. As the boat came alongside each shining serpent, Alexia netted the beast or Fry simply plunged an arm into the ocean and snatched it up with his hands, flinging it into the bow. Then Fry would track its movements—"body-talking" to the snake, as he puts it, engaging in a kind of dance based on a deeply nuanced understanding of how a given species tends to react. Given that he has this dance wired with everything from pit vipers to mambas to king cobras, the relatively sluggish sea snakes are generally no match for him. Grabbing them just so, Fry easily tossed each into a water-filled bin already holding dozens of its friends.
On the night in question, Alexia recalls, "I was the last one standing on the boat, and Bryan was on shore showing some kids our catch." Most sea snakes have such soft muscle tissue, adapted to their loose aquatic movements, that they tend to be awkward on land. As a result, Fry simply kept a respectful
distance from the snake-filled bin while he pointed out a venomous horned sea snake, a species Fry had never caught before. What he did not know is that horned sea snakes—for which there was no known antivenom—have unusually hard muscles. Just as Fry said, "Now that one will kill you," the snake did something no other sea snake, in Fry's experience, could possibly have done—it flicked its body upward, and buried its fangs in Fry's finger.
"I watched the sides of its head go inward," Fry says, "that nice concave look they get when the fangs empty." Right then, he says, "you look down, and you see that blood, and you know to every cell in your body that your mortality is under direct challenge."
Anything you can imagine going wrong in the body, some snake out there somewhere has a toxin that'll do exactly that," Fry says, from his Melbourne home, a wooden cottage bordering a eucalyptus forest. At any given moment, the Fry residence better resembles a zoo than the cozy home of a devoted couple. Their living room alone houses 35 giant monitor lizards in cages. Other rooms are cluttered with death adders, vipers, and various sea snakes. "We don't have a lot of friends come over, for some reason," Fry admits. He feeds the animals "mouse-cicles"—frozen rats from the animal labs at the university—and he regularly milks venom from many of them. The toxins in these venoms, Fry says, "do things that are just not right. Like the Burmese population of the Russell's viper—the little bastards cause uncontrollable hemorrhaging of your pituitary gland, where all our sex hormones are controlled. So if you are unlucky enough to survive the bite, you can be permanently impotent and sterile. I've looked at the clinical pictures. You have 40-year-old men who have lost all pubic hair, all facial hair, and they're experiencing a fate worse than death. It's really the anti-Viagra, and that's just odd."
Snake venoms are also remarkable, Fry points out, for the sheer number of catastrophic effects that they can cause simultaneously. The venom of the seven-foot-long Australian inland taipan, for example, carries more than 50 toxins, including some that abruptly lower blood pressure, others that block nerve receptors in skeletal and peripheral muscle, others that actually destroy nerves, and still others that attack blood cells. "On top of that," Fry says, "you have just absolutely huge amounts of it being pumped into you, so there's not a lot you can do."
It is precisely this complexity, however, that has led to Fry's most interesting discoveries. For decades it was assumed that snake venom had evolved separately in a range of snake species, based on the fact that many venomous snakes had close nonvenomous relatives. But modern gene sequencing technology has allowed Fry to show that snake venom had a single point of biological origin, in the earliest of snakes, and that even the apparently nonvenomous snakes have active venom glands—they just lack a means for delivering it. Fry's research has raised the number of known venomous snakes from around 200 to 2,000-plus. He has also shown that the venom mix evolves more quickly than the snake species itself, constantly morphing as part of a predator-prey arms race. The mechanism for this is what's known as gene recruitment, in which genes typically expressed in other bodily functions—such as digestion—get expressed accidentally in the venom gland. If the accident makes the venom more lethal, then natural selection will encourage its repetition.
"Like with rattlesnake bites," Fry says, "which are notorious for turning your arm basically into goo. They've recruited a very powerful digestive enzyme but they've changed it [so that] in some versions it's more powerful in terms of chewing up the flesh, but in other versions it chews up the blood."
Further mutation over time may even heighten a gene's power as a toxin, as with two common blood-clotting agents that have been recruited into snake venom. "The only changes that have occurred," Fry says, "are that the body can't break down [the toxins] as quickly, so it just keeps clotting blood and clotting blood and clotting blood. That's one of the reasons you don't want to get bitten by a taipan. They do very, very, very bad things to your blood, causing millions of tiny little clots, which do a wonderful job of knocking out your kidneys—the first domino in a horrible series called multiple organ failure. And then at the same time, they've used up all your clotting factors, so you can't clot anymore, and you start bleeding out of places you don't want to bleed out of. It's just . . . what they do to you, it's just not right!" This is, of course, exactly what fascinates Fry. "The toxins," he says, "are an unusual combination of extremely potent and absolutely laser-guided accuracy."
Read more about Dr. Fry's snake-venom research the September 2005 issue of Adventure magazine.