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Skeptimedia

Skeptimedia is a commentary on mass media treatment of issues concerning science, the paranormal, and the supernatural.

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Skeptimedia replaces  Mass Media Funk and Mass Media Bunk. Those blogs are now archived.

The deadliest animal on the planet

16 Feb 2010. The mosquito is often credited with being the deadliest animal on the planet because it causes the death of perhaps 2,000,000 people each year from malaria.* A whale may kill 2,000,000 krill in a single swallow. If, as evolutionary biologists and some animal rights activists tell us, humans are not superior to any other creature that has evolved, then whales may deserve the title of deadliest animal. The distinction depends on what one means by 'superior,' I suppose. If by 'superior' one means that Nature or God endowed humans with more being than bestowed on krill, then the idea of one species being superior to another sounds like gibberish. If, on the other hand, one means by 'superior' that one species has evolved the capacity to reason and construct concepts like 'superior," then homo sapiens seems obviously superior to both krill and the whale.

From one perspective, the most deadly animal on the planet would be the species that kills the most animals, say, annually. From another perspective, the most deadly animal is the one that kills the most humans. Humans kill many of their own kind in wars, revolutions, crime sprees, accidents, and so on, but I doubt we kill more than 2,000,000 of our own kind each year. According to WikiAnswers, "About 500 people die in a day [from war] so about 1,825 people die in a year. Do the math, 500 x 365 = 182,500." I don't think we can trust this answer if the person giving it doesn't know the difference between 1,825 and 182,500. Worse, no reference is given for the 500 number. Anyway, there would have to be about 5,480 humans killed by humans each day to match the number killed annually by malaria.

Several sources put the number of murders a day in the U.S. at about 50. According to one site, a place called Lesotho is the worst place in the world for death by murder: 141 per 100,000 per year. Lesotho is surrounded by South Africa and has about 1.8 million inhabitants. I calculate that there are about 7 murders a day in Lesotho. The point is that even though it is impossible to get an accurate count on how many murders there are each day or year on the planet, it is unlikely that the sum is going to come anywhere near the number killed by mosquitoes each day.

Of course I support efforts to reduce the homicide rate around the globe, but we could probably save more lives if we worked on ways to prevent the mosquito from transmitting malaria. Professor John Carlson, a molecular biologist at Yale University, and his team of researchers have been doing just that. He notes that mosquitoes find us through their sense of smell. His team has identified and isolated 72 types of odor receptors on the antennae of the mosquito, 27 of which are tuned to detect chemicals found in perspiration and in bacteria that live on the skin.*

Allison Carey, a Ph.D. student at Yale, and her colleagues:

painstakingly inserted each gene in turn into a breed of mutant fruit flies that lack a sense of smell. This endowed the antennae of the recipient flies with the mosquito receptor, sensitizing their antennae to any chemicals to which that receptor responded. And by studying just one gene at a time, the full spectrum of odors detected by that receptor could be identified.*

Identifying which receptors the mosquitoes use to navigate their way toward us could help us devise new ways of repelling, confusing, and trapping the insects. "We're now screening for compounds that interact with these receptors," says Carlson. "Compounds that jam these receptors could impair the ability of mosquitoes to find us. Compounds that excite these receptors could help to lure mosquitoes into traps or repel them. The best lures or repellents may be cocktails of multiple compounds."

Even though I don't live in a part of the world where malaria is a problem, I am grateful to those scientists working on ways to prevent diseases spread by these deadly creatures. Mosquitoes seem to be a problem no matter where one lives. Around here, they are known to transmit the West Nile virus. These little critters can carry viruses that inflame the human brain or blood vessels. Anyone working to prevent these creatures from spreading pain, suffering, and death deserves our gratitude. By any standard, scientists working to eradicate the effects of these insects are superior to mosquitoes.

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* Wikipedia gives the number of annual deaths from malaria at "between 1 and 3 million." The Naked Scientists give the number 2,000,000. TimesOnline gives the number as "up to 3,000,000" and says that 500,000,000 in the world's tropical regions have contracted the disease. Another source says there are 250,000,000 cases each year. Needless to say, these numbers can't all be right.

further reading

'Malaria and weak bones' may have killed Tutankhamun Scientists spent the last two years scrutinizing the mummified remains of the 19-year old pharaoh to extract his blood and DNA. They found traces of the malaria parasite in his blood, the Journal of the American Medical Association says.

New way to fight malaria, bacteria found "Illinois medical scientists say they've discovered an unusual chemical reaction that allows malaria parasites and many bacteria to survive. The researchers, led by Professor Eric Oldfield, said they also have learned how to exploit that chemical reaction by developing a potent inhibitor for it."

Genomic warfare to counter malaria drug resistance "Scientists battling malaria have earned a major victory. According to a Nature Genetics study, an international group of researchers has used genomics to decode the blueprint of Plasmodium falciparum – a strain of malaria most resistant to drugs that causes the most deaths around the world. The discovery may lead to advanced pharmaceuticals to fight the disease and prevent drug resistance among the 250 million people infected by malaria each year."