Black mambas are fast, agile, nervous, and big, reaching lengths up to fourteen feet. Among venomous snakes, only the king cobra grows longer. Mambas and cobras, their hooded cousins, belong to the family Elapidae and share a potent neurotoxic venom. Its effects are dramatic. A victim"s neurons no longer transmit messages, mus - cles fail to respond to the simplest command, and bitten animals asphy xiate as the venom scrambles nerve signals that tell the diaphragm to expand and contract.
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Kill Bill, a macabre comedy film, features a.s.sa.s.sins named after deadly snakes: Black Mamba, Cottonmouth, Copperhead, and Sidewinder. Two thumbs-up for Tarantino"s powerful ode to motherhood.
As Layton"s quick death indicates, black mamba venom is powerful: The venom from a single bite can kill 9,400 lab mice. But mambas aren"t the toxicity champs, not by a long shot; at least twenty-two other snakes pack more of a wallop. At the top of the list is Australia"s inland taipan. This shy, inoffensive serpent-which the late Steve Irwin let tongue-flick his cheek on one episode of The Crocodile Hunter The Crocodile Hunter-can snuff out 100,000 lab mice with the venom from a single bite.
These toxins are much more powerful than snakes seem to need. It"s like they"re rabbit hunting with a bazooka. And the mystery deepens when you consider how costly venom is to produce. One study showed that after being "milked," rattlesnakes and other pit vipers jack up their metabolic rate by 11 percent for at least three days to refill their glands. So shouldn"t natural selection discourage snakes from making excessively toxic venom?
It should, and it does. Snakes aren"t as loose with their venom as we may think.
Mamba venom did not evolve to kill humans or lab mice. Prey animals are tough, so snakes count on their venom to immobilize their prey, and to do so fast. fast. Many venomous snakes tackle feisty, sharp-toothed prey that can outweigh them by 50 percent- formidable foes, especially for animals without arms or legs. A single bite from a wood rat, for example, can snip right through a western diamondback rattlesnake"s spine. Many venomous snakes tackle feisty, sharp-toothed prey that can outweigh them by 50 percent- formidable foes, especially for animals without arms or legs. A single bite from a wood rat, for example, can snip right through a western diamondback rattlesnake"s spine.
Venomous Dinosaurs? A recent fossil a.n.a.lysis provides the most detailed evidence yet that some dinosaurs hunted with venom. Sinornithosaurus, a carnivorous Chinese dinosaur that lived 65-100 million years ago, had fanglike front teeth and a large bony pocket in its upper jaw that likely contained a venom gland. In modern venomous taxa, this type of fang discharges venom along a groove on the outer surface of the tooth. A recent fossil a.n.a.lysis provides the most detailed evidence yet that some dinosaurs hunted with venom. Sinornithosaurus, a carnivorous Chinese dinosaur that lived 65-100 million years ago, had fanglike front teeth and a large bony pocket in its upper jaw that likely contained a venom gland. In modern venomous taxa, this type of fang discharges venom along a groove on the outer surface of the tooth.
The hypertoxicity of a rattlesnake"s venom helps it prevent this personal tragedy by knocking the rat out in a matter of seconds. The rattlesnake does not care whether his bite could could dispatch a hundred lab mice, or a thousand. All that matters is that it dispatches one rat with a minimum of muss and fuss before the rat has a chance to dispatch him. Super-toxic venom can thus be thought of as a defensive adaptation: It helps keep snakes safe from prey. dispatch a hundred lab mice, or a thousand. All that matters is that it dispatches one rat with a minimum of muss and fuss before the rat has a chance to dispatch him. Super-toxic venom can thus be thought of as a defensive adaptation: It helps keep snakes safe from prey.
The threat of prey retaliation has been important in snake evolution. For example, many venomous species-including rattlesnakes-instinctively strike and release rodents, then hang back and wait for the reeling animal to keel over. Powerful venom prevents dinner from staggering too far off By contrast smaller less dangerous prey such as lizards are often simply choked down, still struggling.
Extreme toxicity can do more than knock prey out. For example, it can-and often does-help snakes digest their dinners. This is a big deal to serpents, which swallow large animals whole.
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Think about that western diamondback again. It strikes a wood rat, tracks the dying animal by homing in on the scent of its own venom, and swallows the prey in one long gulp. Snakes don"t chew their food, so now the snake has an intact rodent clogging its gut.
Such a meal, tempting as it is, would rot inside us before we had a chance to process it. The rattlesnake, however, has an edge: Its venom is packed with proteins that break down tissue. The snake starts digesting the rat from the inside out the moment its inch-long fangs penetrate the rodent"s furry flesh. Tissue-dissolving venom is a key adaptation that allows rattlesnakes and other vipers to consume absurdly large prey.
The bite of a juvenile snake, as most hikers know, can be more dangerous than the bite of an adult. Young snakes are more nervous and have not yet learned to conserve ammunition!
Another reason snake venoms are so toxic is that prey animals are tough. Animals often evolve a degree of resistance to their predators. California ground squirrels, for example, have proteins in their blood that blunt the effects of rattlesnake venom. Sure, a black mamba bite can snuff 9,400 lab mice. But a true a.s.sessment of mamba venom toxicity would measure its power to kill natural prey such as African rats. These experiments are seldom done, for it is far easier to work with common, inbred lab mice. But it"s a sure bet that venom from one mamba bite cannot take out 9,400 wild African rats.
Hunter and hunted are engaged in a chemical arms race and have been for millions of years. Lab mice, and the unfortunate Nathan L ayton, never joined this race and are pretty much defenseless. Using them to gauge the strength of mamba venom is like testing a Tomahawk missile against a leather shield. The real-world potency of venom is likely far less than our inflated, artificial estimates.
So give snakes a break. Only about 10 percent of the world"s three thousand snake species are venomous enough to be dangerous to man, and they"re dangerous for good reason: They"re as nasty as natural selection dictates they should be. Yet they"re merciful, too. Remember the poor wood rat that became a meal for our western diamondback? He was unconscious in less than a minute and dead in five. As deaths go, you could do a lot worse.
REFERENCES:.
J. E. Biardi, D. C. Chien, and R. G. Coss, "California ground squirrel (Spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins." Journal of Chemical Ecology Journal of Chemical Ecology 31 (2006), 2501-2518. 31 (2006), 2501-2518.
H. W. Greene, Snakes: The Evolution of Mystery in Nature Snakes: The Evolution of Mystery in Nature (Berkeley: University of California Press, 1997). (Berkeley: University of California Press, 1997).
H. Heatwole and N. S. Poran, "Resistances of sympatric and allopatric eels to sea snake venoms," Copeia Copeia (1995) 136-147. (1995) 136-147.
M. D. McCue, "Cost of producing venom in three North American pit viper species," Copeia Copeia (2006), 818-825. (2006), 818-825.
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WEIRD SCIENCE: HUMANS DATING CHIMPSThe idea of humans and chimpanzees swapping genes has been around for decades, but a 2006 Nature Nature paper paper1 provides hard evidence: "The genome a.n.a.lysis revealed big surprises, with major implications for human evolution," said coauthor and Harvard biologist Eric Lander. The human-chimp speciation occurred slowly, with episodes of hybridization between the emerging species that left a striking impact on the X chromosome. According to Australian anthropologist Colin Groves, species interbred in the wild quite often; even today it could be possible for humans and chimps to have s.e.x and produce offspring, although there would be provides hard evidence: "The genome a.n.a.lysis revealed big surprises, with major implications for human evolution," said coauthor and Harvard biologist Eric Lander. The human-chimp speciation occurred slowly, with episodes of hybridization between the emerging species that left a striking impact on the X chromosome. According to Australian anthropologist Colin Groves, species interbred in the wild quite often; even today it could be possible for humans and chimps to have s.e.x and produce offspring, although there would be ethical problems ethical problems.
CHAPTER 10.
FATHER KNOWS BEST.
Father to son: "Glad I stayed around to father you you. Doesn"t that make you worry? "
Readers share family stories showing that Father Knows Best-except when he doesn"t. Darwinian dads play with fire-fireworks, dynamite, gas, and ovens-and with ice, hauling refrigerators and hopping icebergs. These fathers survived, they reproduced, and they can only hope that the offspring did not inherit their questionable judgment!
Father (n.): male who begets childrenPapa, pops, daddy, dad, padre, papi, abu, baba, sire, "rent, progenitor, antecedent, forebearer, paterfamilias, patriarch Why I"m the Last of Nine Children * My Father, the PhD * Mr. Tinker * Popsicle * Blast from the Past * Volunteer "Fire" Man [image]
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Darwin Award Winner: Why I"m the Last of Nine Children Unconfirmed Personal Account Featuring a father, fireworks, vehicles, and a living Darwin!
How my father eliminated himself from the gene pool
My father tried various ways to remove himself from the gene pool. Most methods were mundane: slow suicide by tobacco, alcohol, bad diet. But one incident stands out, caused by Dad"s habit of driving down the road while lighting firecrackers off his cigarette. Considering Dad"s Darwinian judgment, it was amazing his DNA was so successful.
He enjoyed throwing them out the window as he drove down the street. For convenience he kept the firecrackers in his lap. The fuses were wound together, so he would unwind one, light-throw-BANG! Unwind another, light-throw- Unwind another, light-throw-BANG! You get the picture. Uh-huh. You get the picture. Uh-huh.
Given time, a person such as this can be relied upon to cause himself harm.
Those who study Darwin know that, given time, a person such as this can be relied upon to cause himself harm. Dear old Dad accidentally added a bounce to his light throw-bang sequence: The firecracker sequence: The firecracker bounced bounced off the door and back into his lap! A few firecrackers popped, setting of the remaining firecrackers, and there was some prettycreative driving for a while, amid much smoke and cussing. off the door and back into his lap! A few firecrackers popped, setting of the remaining firecrackers, and there was some prettycreative driving for a while, amid much smoke and cussing.
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I do not know the extent of the damage to Dad"s reproductive organs-but I do do know I was the last of nine children! know I was the last of nine children!
Reference: Anonymous daughter WEIRD SCIENCE: SIX INTRIGUING HUMAN TRAITSIt is not obvious how some aspects of human nature enhance biological success. From the magazine New Scientist New Scientist, some of our quirky foibles that defy explanation:* Blushing. Charles Darwin himself struggled to explain a response that puts humans at a social disadvantage.* Laughter.* Dreams.* Superst.i.tions.* Kissing.* Teenagers. Even the great apes move smoothly from juvenile to adult; why then do humans spend an agonizing decade skulking around in hoodies and ignoring their elders?
At-Risk Survivor: My Father, the PhD Unconfirmed Personal Account Featuring a father, fire, a chainsaw, and more
"We have more degrees, but less sense; more knowledge but less judgment."
-the Dalai Lama
Let an amused daughter tell you about her sire . . .
This weekend was the final straw. Being an extremely cost-conscious person, Dad decided to put half a can of varnish in the toaster oven to liquefy it, as this was the cheapest cheapest approach. You guessed it-the stuff caught fire! I found him in front of the flaming oven contemplating grabbing the can with his bare hands. Two-foot flames were shooting out of it, causing me to utter a line spoken far too many times in our home: approach. You guessed it-the stuff caught fire! I found him in front of the flaming oven contemplating grabbing the can with his bare hands. Two-foot flames were shooting out of it, causing me to utter a line spoken far too many times in our home:
"What in G.o.d"s name were you thinking?"
Father"s attempts at Darwin fame have included 1. Tipping a small boat while fishing on a lake, nearly drowning my brother and himself. At the time, I thought Mom was being too hard on him when she said it was his own fault that he was in the hospital. I have since revised my judgment.[image]2. Removing a branch from a locust tree by climbing a ladder with a running running chainsaw. The branch was not tied off properly, so it fell onto the roof that he was trying to avoid. chainsaw. The branch was not tied off properly, so it fell onto the roof that he was trying to avoid.3. Rolling a lawn tractor on top of himself by mowing a roadside ditch at a steep angle, resulting in a broken rib-and poison ivy for me, because I spent ten minutes thrashing around in the vegetation while we tried to roll the tractor off Dad. Again. Again. 4. Lighting a fire in a bas.e.m.e.nt trash burner 4. Lighting a fire in a bas.e.m.e.nt trash burner that was not connected to an exhaust pipe. that was not connected to an exhaust pipe. The fire department loves us. The fire department loves us.5. Wandering off to watch the evening news after setting some water to boil in an aluminum Dutch oven. Note that the Merck Index lists the melting point of aluminum as 660C. When Mom discovered the situation, the sides were glowing bright red, the bottom was melted out, and the kitchen wall was smoking.A reader who works in the foundry industry warns, "Aluminum does not glow red when it is heated. Molten aluminum does not glow, and that makes it extremely dangerous."6. Testing the efficacy of old nitroglycerin tablets by swallowing three at once to see if they still worked. I did say he was cheap-er, cost conscious. The EMS came to the rescue because his blood pressure had dropped to an undesirable level and he had pa.s.sed out at the kitchen table. Mere minutes before, he had been planning a drive to the doughnut shop. Thank G.o.d he didn"t make it to the car before his blood pressure dropped!
He may not yet have used up nine lives, but my father, the PhD, appears to have a running start on Darwin infamy.
Reference: Anonymous daughter [image]
Reader Comments
"Working with PhDs, I"m completely not not surprised by this . . ." "I have always said, the more degrees, the dumber." surprised by this . . ." "I have always said, the more degrees, the dumber."
WENDY"S WORDS OF WISDOMMost of the chairs in my house are on wheels; I often stood on them to reach high places. One day I read the Darwin Award about a fellow who stood on a rolling chair to fill his bird feeder . . . and rolled right off the twenty-fourth floor balcony. I no longer stand on those chairs in front of windows!Learn from the mistakes of others.You won"t live long enough to make them all yourself.
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At-Risk Survivor: Mr. Tinker Unconfirmed Personal Account Featuring a do-it-yourself father
If you ever considered your male parent a doofus, read on.
You might feel better.
My father-in-law tinkers and most often fixes things. I have seen him take apart toasters, motors, electronics, and power washers. He often has several projects on the go. One day he came home with a neighbor"s broken microwave and disappeared into his workshop to suss out the problem.
He still tinkers today, but we keep a closer eye on him.
A while later I heard weird noises coming from the workshop, and peeked in. The microwave was now working fine but its front door was missing. The machine was running, and he had his head tucked inside the oven!
I ran in and pulled the plug.
He did not take himself out of the gene pool (not then) but the microwaves may have increased the odds of cancer: A few years later he developed a brain tumor. It was successfully removed and he still tinkers today, but we keep a closer eye on him.
See, there are worse parents . . .
Reference: Anonymous son-in-law At-Risk Survivor: Popsicle Unconfirmed Personal Account Featuring a father, water, alcohol, and a Double Darwin attempt!
In the mid-eighties my father sailed on the research ship Regina Maris Regina Maris to study whales in Greenland. One night he noticed there were a lot of icebergs floating by the boat. Icebergs! to study whales in Greenland. One night he noticed there were a lot of icebergs floating by the boat. Icebergs!
After drinking several beers too many with a friend, he and the friend decided to do something stupid. A quick hop onto an iceberg proved that they could stand on it. So my dad decided to hop from iceberg to iceberg with his friend until they reached the nearest village two miles away. Hop after hop, they made their way across the ice floe. As the lights of the village and the sh.o.r.eline grew nearer, they grew colder and began to pick up the pace. Alas, in their hurry, they accidentally hopped together onto one small iceberg. It broke under their combined weight, plunging them into the icy salt water where they quickly sobered up.
Dad decided to hop from iceberg to iceberg.
After thrashing about in the ch-ch-chilly water for several interminable minutes, they managed to climb out onto another iceberg, and carefully hopped the rest of the way to sh.o.r.e. The men limped into the village, where they were admitted to the hospital. Treated for hypothermia and a touch of frostbite and released little worse for the wear, to this day my dad never goes into the ocean
Reference: Anonymous son [image]
At-Risk Survivor: Blast from the Past Unconfirmed Personal Account Featuring a father, an uncle, vehicles, and dynamite!
MID-1950 s , about their youth and shared a rather Darwinian story. In their twenties, they succeeded in a.s.sembling one great car out of three junkers. After they accomplished this, they had enough parts leftover to make a second working car-but only barely. This car was missing most of its floorboards, so they could see the ground flash past while driving. They called this a feature rather than a flaw, and decided to have fun with it.
To make the dynamite sticks safer, they shortened the fuses.
In the fifties, high-powered explosives were still easy to acquire. So, with quarter sticks of dynamite at hand, my future father and his brother drove around throwing dynamite through the gaps in the floorboards, and basically scaring the daylights out of people in cars behind them. THIS WAS FUN! They even shortened the fuses to make sure that the sticks would "safely" explode before the car behind them drove over them.
When I heard this story, my first response was, "Weren"t you concerned about the gas tank below you?" To my amazement they both looked rather surprised, exchanged glances, and said, "We never thought of that!" My grandfather just laughed and walked out of the room.