Read The Darwin Awards Next Evolution: Chlorinating the Gene Pool Online
Authors: Wendy Northcutt
Tags: #Humor, #Form, #Anecdotes, #General, #Stupidity, #Essays
The Darwin Awards Next Evolution: Chlorinating the Gene Pool (8 page)
At the top of the cliff the four remaining kids telephoned for help, but the cliff was so remote that we couldn’t get through. Instead of running for help we decided to winch him up ourselves. We set about digging up the peg he was attached to. When it finally came free, there was only one person holding it, and he was pulled over the cliff by the weight of the first boy.
Sensibly, he still had his harness on, but the forty-five-foot drop he endured nearly knocked this boy out. Meanwhile, the extra forty-five feet of rope let the first boy plunge into the ocean, where he unfortunately drowned.
The last three boys on the cliff summoned help from the Coast Guard. Half an hour later a large Sea King helicopter attempted to lift the dangling boy to safety. By this point the knot that tied the rope around the boy’s waist had come loose, and he was hanging on for dear life.
Whirling helicopter blades build up a massive amount of static electricity as they beat against the air. Each helicopter therefore carries a cable to ground itself after a flight. As that cable approached the boy, he grabbed for it, heedless of people shouting warnings from the helicopter. When he did grab ahold of the cable, the electric shock blew him against the cliff, and he fell into the sea.
Fortunately, he did not drown. He was airlifted to a hospital, where he made a full recovery.
Six years later I still have the scar on my hand where I touched that earthing cable. I owe my life to the work of the Coast Guard that day. Thank you, Coast Guard, for helping idiots like me stay alive long enough to tell the story to other idiots.
Cheers!
Reference: Eyewitness account by Alexander Anderson (a pseudonym)
“The problem with the gene pool is that there is no lifeguard.”
—Steven Wright
By Michelle Keefer
M
osquitoes—the bane of many a camping trip and barbecue—have been haunting the human race for millennia. But bloodsucking isn’t as easy as it seems. These insects rarely get the credit they deserve for their highly specialized methods of overcoming the obstacles of blood feeding. They are easy to dismiss with the flick of a hand, without stopping to think about the amazing ways mosquitoes have evolved to survive on your blood.
Painkillers
You look down and see a fat and happy mosquito feeding on your arm, to which you were completely oblivious a moment before. How did that mosquito suck that much blood from your defenseless arm without you noticing? After all, mosquitoes are basically flying needles, and you can feel a needle prick! A mosquito doesn’t want its host to know it is feeding—at best its meal would be interrupted; at worst it would be flattened. So mosquitoes inject painkillers with their saliva when they penetrate the skin, and their victims remain unaware of their piercing proboscises.
Vasodilators
If you’ve managed to tolerate watching your mosquito sitting there sucking up your precious bodily fluids, then another question may occur to you. “How did she slurp up that much blood so quickly?” Enter another ingenious component of mosquito spit—vasodilators. Generally, an injured blood vessel will contract to decrease blood loss. Obviously, this is not good for the poor little mosquito. The longer it takes her to fill up, the more likely her meal will be interrupted. So she injects vasodilators, similar to nitroglycerin, a commonly prescribed drug that lowers blood pressure. Vasodilators relax and expand blood vessels and permit increased flow, so the mosquito can obtain her meal before your patience runs out and you dismiss her in whichever way you feel most fitting.
Aedes aegypti,
the mosquito that transmits the yellow fever virus, injects two vasodilators in its spit, proteins that are similar to a mammalian signaling protein. In blood vessels the injected proteins encourage the release of nitric oxide from the inner lining of blood vessels, which in turn causes the smooth muscle of the vessel wall to relax. Mosquito vasodilators mimic your own proteins, to relax your vessels and continue the flow of tasty blood into the mosquito.
Anticoagulants
A useful ability of blood, as I am sure you are aware, is its capability to clot—a property that threatens the life of a bloodsucking insect! Consider, if you will, the mosquito currently filling up on your arm.
Imagine what would happen if your body reacted to the puncture as usual, by activating the blood-clotting system? The mosquito continues to feed…until it sucks up a clot, blocking its needlelike proboscis. The “corked” mosquito now has quite a problem on its hands. It is unable to feed. To avoid this perilous predicament mosquitoes inject anticoagulants to keep dinner flowing.
After Mrs. Mosquito settles on your arm, she spends some time probing around for a vessel until she finds one. There are studies on this probing behavior of mosquitoes. You do not feel these shallow punctures because the proboscis is slender enough to slip between the nerve cells.
Our friend
Aedes aegypti
employs a protein that counteracts a specific protein in the coagulation cascade, factor Xa, which activates the fibrous molecule that forms a blood clot. The mosquito protein that puts a stop to clotting is similar to one your own body produces, which maintains the crucial balance between excessive bleeding and excessive clotting by inhibiting factor Xa. The mosquito injects this anticoagulant into your vessel as it starts feeding. When your skin is pierced, your body responds by activating the coagulation cascade. But the mosquito has played its trump card. It has already injected a neutralizing agent that inhibits factor Xa, preventing clot formation by halting the enzymatic cascade.
Immunomodulators
The mosquito has taken her fill and has departed. As you contemplate the mysteries of mosquito spit, you suddenly notice the reason these insects are so loathed. An itchy bump, increasing in size and annoyingness, has emerged on your arm. This allergic reaction is the first sign of your immune system’s response to the foreign proteins in your blood vessel from the mosquito spit.
Your body is not at all pleased with those weird proteins injected by the hungry mosquito. An immune response is initiated by the antibodies against mosquito saliva that your body produced the very first time you were bitten. Your cells release a variety of molecules to fight the invaders. Histamines dilate blood vessels to allow immune cells access to the mosquito proteins, causing redness and swelling. Histamine also irritates your nerve endings, resulting in an itch. Leukotrienes recruit immune cells and sustain the allergic reaction, extending the life of that aggravating itchy bump.
Which leads to the most ingenious parts of a mosquito’s pharmacological spit cocktail—the immunomodulators. Vasodilators, anticoagulants, and other salivary proteins temporarily suppress your immune system. These immunosuppressants decrease immune cell propagation, histamine secretion, and the number of natural killer cells and macrophages. This benefits the mosquito by delaying the immune response, so the mosquito can finish her meal before you notice the little bloodsucker.
The Perfect Disease Transmitters
Mosquito bites are annoying, but mosquito spit causes no serious harm. However, mosquitoes can transmit West Nile virus, yellow fever, dengue fever, malaria, and other debilitating diseases. As a side effect of suppressing our immune systems, mosquito spit makes it easier for these diseases to infect us. Studies show that mice injected with both pathogen and mosquito saliva have higher infection rates than those injected with pathogen alone, indicating that mosquito saliva does indeed increase the ability of the virus or parasite to infect its host.
The prevention of mosquito-borne diseases is a complex and difficult task. However, some scientists use mosquito spit to their advantage by making vaccines against its proteins! Such a vaccine would decrease the infectivity of the pathogens. Vaccines against proteins in sandfly spit have already been developed to help prevent leishmaniasis. Now scientists are working to develop similar vaccines against mosquito spit to protect against diseases like malaria and West Nile.
So the next time a mosquito decides to nourish her eggs with your precious bodily fluids, take a moment to appreciate the finely tuned system she has evolved to suck your blood. You might also give a nod to the scientists who had to raise mosquitoes (yes, raise mosquitoes!) in order to provide you with this fascinating insight into the Wonders of Mosquito Spit.
Intrigued? Take a closer look at the research:
Champagne, D. E., and J. M. C. Ribeiro, 1994. Sialokinin I and II: Vasodilatory tachykinins from the yellow fever mosquito
Aedes aegypti
.
Proceedings of the National Academy of Sciences USA.
91: 138–142.
Edwards, J. F., S. Higgs, and B. J. Beaty, 1998. Mosquito feeding-induced enhancement of Cache Valley Virus (Bunyaviridae) infection in mice.
Journal of Med Entomology.
35: 261–265.
Gillespie, R. D., M. L. Mbow, and R. G. Titus, 2000. The immunomodulatory factors of bloodfeeding arthropod saliva.
Parasite Immunology.
22: 319–331.
Marquardt, William H.
Biology of Disease Vectors.
2nd edition. Academic Press, 2004.
Stark, K. R., and A. A. James, 1995. A factor Xa-directed anticoagulant from the salivary glands of the yellow fever mosquito
Aedes aegypti
.
Experimental Parasitology.
8(3): 321–331.
Titus, R. G., et al. 2006. The immunomodulatory factors of arthropod saliva and the potential for these factors to serve as vaccine targets to prevent pathogen transmission.
Parasite Immunology.
28: 131–141.
Wasserman, H. A., S. Singh, and D. E. Champagne, 2004. Saliva of the yellow fever mosquito,
Aedes aegypti,
modulates murine lymphocyte function.
Parasite Immunology.
26: 295–306.
Michelle Keefer
has a bachelor’s degree in microbiology from Colorado State University. When she’s not in the lab, she enjoys traveling, riding her motorcycle, playing the guitar, and various nerdier pursuits. Michelle currently lives in Fort Collins with—in no particular order—her cat, her Harley, and her boyfriend.
E
LECTRICAL
E
XTINCTIONS
Zap! Electricity has been part of our daily lives for scant generations, not nearly enough time to come to an evolutionary compromise with its danger. Kites, electric lines, TV power cords, stolen copper, and Tasers…this shocking subject merits a chapter of its own. Electricity surrounds us, and the curious human monkey cannot resist testing the circuits.
Darwin Award: ZAP!
Confirmed True by Darwin
2003, CALIFORNIA
A Los Angeles real estate attorney was skimming leaves from his pool when he noticed a palm frond caught in the power lines. His education had equipped him with sufficient acumen to become a successful litigator, yet he was not shrewd enough to avoid becoming a toasty critter when he reached up with the long metal pole and poked at the palm frond.
Did I mention the power lines?
Our lawyer was, for once, the path of least resistance.
Perhaps as an homage to his litigation skills, his family sued both the utility company and the pool supply store for failure to disclose the danger of poking a metal rod into the power lines.
Reference:
Los Angeles Times,
freerepublic.com,
The True Stella Awards
by Randy Cassingham
